US20140045243A1 - Mutant cells for protein secretion and lignocellulose degradation - Google Patents

Mutant cells for protein secretion and lignocellulose degradation Download PDF

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US20140045243A1
US20140045243A1 US14/005,245 US201214005245A US2014045243A1 US 20140045243 A1 US20140045243 A1 US 20140045243A1 US 201214005245 A US201214005245 A US 201214005245A US 2014045243 A1 US2014045243 A1 US 2014045243A1
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cell
gene
protein
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cellobiose
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Elizabeth A. Znameroski
James H. Doudna Cate
N. Louise Glass
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University of California
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    • C12N9/2405—Glucanases
    • C12N9/2434—Glucanases acting on beta-1,4-glucosidic bonds
    • C12N9/2437—Cellulases (3.2.1.4; 3.2.1.74; 3.2.1.91; 3.2.1.150)
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    • C12N9/2405—Glucanases
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    • C12P19/14—Preparation of compounds containing saccharide radicals produced by the action of a carbohydrase (EC 3.2.x), e.g. by alpha-amylase, e.g. by cellulase, hemicellulase
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    • C12Y302/01—Glycosidases, i.e. enzymes hydrolysing O- and S-glycosyl compounds (3.2.1)
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    • C12Y101/00—Oxidoreductases acting on the CH-OH group of donors (1.1)
    • C12Y101/99—Oxidoreductases acting on the CH-OH group of donors (1.1) with other acceptors (1.1.99)
    • C12Y101/99018—Cellobiose oxidase (1.1.99.18)
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    • C12Y302/01—Glycosidases, i.e. enzymes hydrolysing O- and S-glycosyl compounds (3.2.1)
    • C12Y302/01004—Cellulase (3.2.1.4), i.e. endo-1,4-beta-glucanase

Definitions

  • the present disclosure relates to mutant cells for the production of proteins, such as cellulases, and for the degradation of lignocellulosic biomass.
  • mutant cells and methods for the production of proteins, such as cellulases are provided.
  • Lignocellulosic biomass is an abundant and renewable raw material for biofuel production.
  • the initial conversion of insoluble lignocellulosic biomass into cell-permeable and readily fermentable sugars presents a significant technical challenge and major bottleneck in the biofuel production process.
  • Improved means to overcome this bottleneck are therefore needed to unlock the full potential of lignocellulosic biomass as a versatile energy source.
  • the natural degradation of biomass is achieved by fungal microorganisms through their secretion of lignocellolytic enzymes.
  • the filamentous fungus and laboratory model organism Neurospora crassa N. crassa
  • Neurospora crassa N. crassa
  • filamentous fungi and their lignocellolytic enzymes have great potential as catalysts of biomass degradation in biotechnological production processes.
  • soluble inducers are much less effective.
  • cellobiose the main soluble end product of cellulases, induces cellulases in several species of filamentous fungi, including Hypocrea jecorina ( Trichoderma reesei; T. reesei ) and Aspergillus species ( A. niger, A. nidulans, A. oryzae ) but at much lower levels than cellulose itself.
  • Hypocrea jecorina Trichoderma reesei; T. reesei
  • Aspergillus species A. niger, A. nidulans, A. oryzae
  • one problem with insoluble inducers is that cellulase can adhere to insoluble inducers, resulting in reduced yields of secreted enzyme activity.
  • insoluble biomass matter is a heterogeneous process and access to biomass surfaces is limiting for fungal cells.
  • a large population of cells will be free-floating and not secreting high levels of active cellulase enzymes, due to their lack of contact with inducing plant surfaces.
  • cellular systems are needed that secrete high levels of active proteins after induction with soluble small molecules, such as cellodextrin.
  • mutant cells for increasing secretion of proteins and for the degradation of lignocellulosic biomass.
  • the present disclosure is based, at least in part on the surprising discovery that mutating ⁇ -glucosidase genes and/or the catabolite repressor gene, cre-1, in filamentous fungi, such as Neurospora crassa , results in an increase in the secretion of proteins when induced by cellulosic biomass, such as cellobiose.
  • the activity of ⁇ -glucosidase genes and the cre-1 is involved in the transcriptional regulation of proteins ( FIG. 1 ).
  • one aspect of the present disclosure provides a method for increasing secretion of a protein from a cell, by: (a) providing a mutant cell, where the mutant cell contains inactivating mutations in two or more ⁇ -glucosidase genes; and (b) contacting the mutant cell with cellulosic biomass, where the cellulosic biomass induces the mutant cell to secrete the protein.
  • the mutant cell further contains an inactivating mutation in a cre-1 gene in the cell.
  • Another aspect of the present disclosure provides a method for increasing secretion of a protein from a cell, by: (a) providing a mutant cell, where the mutant cell contains an inactivating mutation in a cre-1 gene in the cell; and (b) contacting the mutant cell with a cellulosic biomass, where the cellulosic biomass induces the mutant cell to secrete the protein.
  • the mutant cell further contains inactivating mutations in two or more ⁇ -glucosidase genes.
  • the cellulosic biomass includes one or more of a polysaccharide, an oligosaccharide, cellulose, microcrystalline cellulose, cellodextrin, cellobiose, cellotriose, cellotetraose, cellopentose, and cellohexose.
  • the cellulosic biomass includes cellobiose.
  • one aspect of the present disclosure provides a method for increasing secretion of a protein from a cell, by: (a) providing a mutant cell, where the mutant cell contains inactivating mutations in two or more ⁇ -glucosidase genes; and (b) contacting the mutant cell with a saccharide, where the saccharide induces the mutant cell to secrete the protein.
  • the mutant cell further contains an inactivating mutation in a cre-1 gene in the cell.
  • Another aspect of the present disclosure provides a method for increasing secretion of a protein from a cell, by: (a) providing a mutant cell, where the mutant cell contains an inactivating mutation in a cre-1 gene in the cell; and (b) contacting the mutant cell with a saccharide, where the saccharide induces the mutant cell to secrete the protein.
  • the mutant cell further contains inactivating mutations in two or more ⁇ -glucosidase genes.
  • the saccharide is selected from a polysaccharide, an oligosaccharide, cellulose, microcrystalline cellulose, cellodextrin, cellobiose, cellotriose, cellotetraose, cellopentose, and cellohexose. In certain embodiments that may be combined with any of the preceding embodiments, the saccharide is cellobiose.
  • the secreted protein is a cellulose-induced protein. In certain embodiments that may be combined with any of the preceding embodiments, the secreted protein is selected from a cellulase, a GH61 enzyme, a cellobiose dehydrogenase, a lactonase, a carbohydrate esterase, a polysaccharide lyase, and a cellulose binding domain-containing protein, and combinations thereof. In certain embodiments that may be combined with any of the preceding embodiments, the secreted protein is a cellulase.
  • the secreted protein is encoded by a gene selected from NCU07340, NCU09680, NCU07898, NCU00762, NCU08760, NCU05057, NCU02240, NCU07190, NCU07898, NCU08760, NCU00206, NCU07143, NCU09491, NCU09664, NCU05598, NCU09764, and NCU05137.
  • the mutant cell further contains an inactivating mutation in at least one ⁇ -mannosidase gene.
  • the mutant cell further contains an inactivating mutation in at least one phospholipase gene or phospholipase-like gene. In certain embodiments that may be combined with any of the preceding embodiments, the inactivating mutations are deletions. In certain embodiments that may be combined with any of the preceding embodiments, the cell is a recombinant cell. In certain embodiments that may be combined with any of the preceding embodiments, the cell is a fungal or yeast cell. In certain embodiments that may be combined with any of the preceding embodiments, the cell is a fungal or yeast cell.
  • the cell is selected from Neurospora crassa ( N. crassa ) cells, Aspergillus nidulans cells, Trichoderma reesei cells, Phanerochaete chrysosporium cells, Sporotrichum thermophile ( Myceliophthora thermophila ) cells, Gibberella zeae cells, Sclerotinia sclerotiorum cells, Botryotinia fuceliana cells, Aspergillus niger cells, Penicillium chrysogenum cells, Schizophyllum commune cells, Postia placenta cells, Aspergillus oryzae cells, and Acremonium cellulolyticus cells.
  • Neurospora crassa N. crassa
  • Aspergillus nidulans cells Trichoderma reesei cells
  • Phanerochaete chrysosporium cells Phanerochaete ch
  • the two or more ⁇ -glucosidase genes are three or more ⁇ -glucosidase genes. In certain embodiments that may be combined with any of the preceding embodiments, the two or more ⁇ -glucosidase genes are four or more ⁇ -glucosidase genes. In certain embodiments that may be combined with any of the preceding embodiments, the two or more ⁇ -glucosidase genes are five or more ⁇ -glucosidase genes. In certain embodiments that may be combined with any of the preceding embodiments, the two or more ⁇ -glucosidase genes are six or more ⁇ -glucosidase genes.
  • the two or more ⁇ -glucosidase genes are seven or more ⁇ -glucosidase genes.
  • the three or more ⁇ -glucosidase genes, four or more ⁇ -glucosidase genes, five or more ⁇ -glucosidase genes, six or more ⁇ -glucosidase genes, or seven or more ⁇ -glucosidase genes include NCU00130, NCU04952, and NCU08755.
  • At least one of the ⁇ -glucosidase genes encodes an intracellular ⁇ -glucosidase. In certain embodiments that may be combined with any of the preceding embodiments, at least one of the ⁇ -glucosidase genes encodes an extracellular ⁇ -glucosidase. In certain embodiments that may be combined with any of the preceding embodiments, the at least one ⁇ -mannosidase gene is NCU00890. In certain embodiments that may be combined with any of the preceding embodiments, the at least one phospholipase gene or phospholipase-like gene is NCU06650.
  • Another aspect of the present disclosure provides a method for increasing secretion of a protein from a cell, by: (a) providing a recombinant cell, where the recombinant cell exhibits reduced expression of at least two ⁇ -glucosidase genes compared to the expression of the at least two ⁇ -glucosidase genes in a corresponding non-recombinant cell; and (b) contacting the recombinant cell with cellulosic biomass, where the cellulosic biomass induces the recombinant cell to secrete the protein.
  • the recombinant cell further exhibits reduced expression of a cre-1 gene compared to the expression of the expression of the cre-1 gene in a corresponding non-recombinant cell.
  • Another aspect of the present disclosure provides a method for increasing secretion of a protein from a cell, by: (a) providing a recombinant cell, where the recombinant cell exhibits reduced expression of a cre-1 gene compared to the expression of the expression of the cre-1 gene in a corresponding non-recombinant cell; and (b) contacting the recombinant cell with cellulosic biomass, where the cellulosic biomass induces the recombinant cell to secrete the protein.
  • the recombinant cell further exhibits reduced expression of at least two ⁇ -glucosidase genes compared to the expression of the at least two ⁇ -glucosidase genes in a corresponding non-recombinant cell.
  • the cellulosic biomass includes one or more of a polysaccharide, an oligosaccharide, cellulose, microcrystalline cellulose, cellodextrin, cellobiose, cellotriose, cellotetraose, cellopentose, and cellohexose.
  • the cellulosic biomass includes cellobiose.
  • Another aspect of the present disclosure provides a method for increasing secretion of a protein from a cell, by: (a) providing a recombinant cell, where the recombinant cell exhibits reduced expression of at least two ⁇ -glucosidase genes compared to the expression of the at least two ⁇ -glucosidase genes in a corresponding non-recombinant cell; and (b) contacting the recombinant cell with a saccharide, where the saccharide induces the recombinant cell to secrete the protein.
  • the recombinant cell further exhibits reduced expression of a cre-1 gene compared to the expression of the expression of the cre-1 gene in a corresponding non-recombinant cell.
  • Another aspect of the present disclosure provides a method for increasing secretion of a protein from a cell, by: (a) providing a recombinant cell, where the recombinant cell exhibits reduced expression of a cre-1 gene compared to the expression of the expression of the cre-1 gene in a corresponding non-recombinant cell; and (b) contacting the recombinant cell with a saccharide, where the saccharide induces the recombinant cell to secrete the protein.
  • the recombinant cell further exhibits reduced expression of at least two ⁇ -glucosidase genes compared to the expression of the at least two ⁇ -glucosidase genes in a corresponding non-recombinant cell.
  • the saccharide is selected from a polysaccharide, an oligosaccharide, cellulose, microcrystalline cellulose, cellodextrin, cellobiose, cellotriose, cellotetraose, cellopentose, and cellohexose. In certain embodiments that may be combined with any of the preceding embodiments, the saccharide is cellobiose.
  • the secreted protein is a cellulose-induced protein. In certain embodiments that may be combined with any of the preceding embodiments, the secreted protein is selected from a cellulase, a GH61 enzyme, a cellobiose dehydrogenase, a lactonase, a carbohydrate esterase, a polysaccharide lyase, and a cellulose binding domain-containing protein, and combinations thereof. In certain embodiments that may be combined with any of the preceding embodiments, the secreted protein is a cellulase.
  • the secreted protein is encoded by a gene selected from NCU07340, NCU09680, NCU07898, NCU00762, NCU08760, NCU05057, NCU02240, NCU07190, NCU07898, NCU08760, NCU00206, NCU07143, NCU09491, NCU09664, NCU05598, NCU09764, and NCU05137.
  • the function of creA/cre-1 is reduced by overexpression of a dominant negative mutant or a protein inhibitor.
  • the recombinant cell further exhibits reduced expression of at least one ⁇ -mannosidase gene compared to the expression of the at least one ⁇ -mannosidase genes in a corresponding non-recombinant cell. In certain embodiments that may be combined with any of the preceding embodiments, the recombinant cell further exhibits reduced expression of at least one phospholipase gene or phospholipase-like gene compared to the expression of the at least one phospholipase gene or phospholipase-like gene in a corresponding non-recombinant cell.
  • gene expression is reduced by siRNA, antisense DNA, quelling, or meiotic silencing.
  • the two or more ⁇ -glucosidase genes are three or more ⁇ -glucosidase genes.
  • the two or more ⁇ -glucosidase genes are four or more ⁇ -glucosidase genes.
  • the two or more ⁇ -glucosidase genes are five or more ⁇ -glucosidase genes.
  • the two or more ⁇ -glucosidase genes are six or more ⁇ -glucosidase genes. In certain embodiments that may be combined with any of the preceding embodiments, the two or more ⁇ -glucosidase genes are seven or more ⁇ -glucosidase genes.
  • the three or more ⁇ -glucosidase genes, four or more ⁇ -glucosidase genes, five or more ⁇ -glucosidase genes, six or more ⁇ -glucosidase genes, or seven or more ⁇ -glucosidase genes include NCU00130, NCU04952, and NCU08755.
  • at least one of the ⁇ -glucosidase genes encodes an intracellular ⁇ -glucosidase.
  • At least one of the ⁇ -glucosidase genes encodes an extracellular ⁇ -glucosidase.
  • the at least one ⁇ -mannosidase gene is NCU00890.
  • the at least one phospholipase gene or phospholipase-like gene is NCU06650.
  • the cell is a stable cell line or a transiently transfected cell.
  • the cell is a fungal or yeast cell.
  • the cell is a filamentous fungus of the ascomycete or basidiomycete species. In certain embodiments that may be combined with any of the preceding embodiments, the cell is selected from Neurospora crassa ( N.
  • Aspergillus nidulans cells Trichoderma reesei cells, Phanerochaete chrysosporium cells, Sporotrichum thermophile ( Myceliophthora thermophila ) cells, Gibberella zeae cells, Sclerotinia sclerotiorum cells, Botryotinia fuceliana cells, Aspergillus niger cells, Penicillium chrysogenum cells, Schizophyllum commune cells, Postia placenta cells, Aspergillus oryzae cells, and Acremonium cellulolyticus cells.
  • mutant cell containing inactivating mutations in two or more ⁇ -glucosidase genes, where cellulosic biomass induces the cell to secrete higher levels of a protein than a corresponding cell lacking said mutation in the two or more ⁇ -glucosidase genes.
  • the mutant cell further contains an inactivating mutation in a cre-1 gene in the cell, where cellulosic biomass induces the cell to secrete higher levels of a protein than a corresponding cell lacking the mutation in the cre-1 gene.
  • the mutant cell further contains an inactivating mutation in at least one ⁇ -mannosidase gene, where cellulosic biomass induces the cell to secrete higher levels of a protein than a corresponding cell lacking the mutation in the at least one ⁇ -mannosidase gene.
  • the mutant cell further contains an inactivating mutation in at least one phospholipase gene or phospholipase-like gene, where cellulosic biomass induces the cell to secrete higher levels of a protein than a corresponding cell lacking the mutation in the at least one phospholipase gene or phospholipase-like gene.
  • the cellulosic biomass includes one or more of a polysaccharide, an oligosaccharide, cellulose, microcrystalline cellulose, cellodextrin, cellobiose, cellotriose, cellotetraose, cellopentose, and cellohexose.
  • the cellulosic biomass includes cellobiose.
  • mutant cell containing inactivating mutations in two or more ⁇ -glucosidase genes, where a saccharide induces the cell to secrete higher levels of a protein than a corresponding cell lacking said mutation in the two or more ⁇ -glucosidase genes.
  • the mutant cell further contains an inactivating mutation in a cre-1 gene in the cell, where a saccharide induces the cell to secrete higher levels of a protein than a corresponding cell lacking the mutation in the cre-1 gene.
  • the mutant cell further contains an inactivating mutation in at least one ⁇ -mannosidase gene, where a saccharide induces the cell to secrete higher levels of a protein than a corresponding cell lacking the mutation in the at least one ⁇ -mannosidase gene.
  • the mutant cell further contains an inactivating mutation in at least one phospholipase gene or phospholipase-like gene, where a saccharide induces the cell to secrete higher levels of a protein than a corresponding cell lacking the mutation in the at least one phospholipase gene or phospholipase-like gene.
  • the saccharide is selected from a polysaccharide, an oligosaccharide, cellulose, microcrystalline cellulose, cellodextrin, cellobiose, cellotriose, cellotetraose, cellopentose, and cellohexose. In certain embodiments that may be combined with any of the preceding embodiments, the saccharide is cellobiose.
  • the secreted protein is a cellulose-induced protein. In certain embodiments that may be combined with any of the preceding embodiments, the secreted protein is selected from a cellulase, a GH61 enzyme, a cellobiose dehydrogenase, a lactonase, a carbohydrate esterase, a polysaccharide lyase, and a cellulose binding domain-containing protein, and combinations thereof. In certain embodiments that may be combined with any of the preceding embodiments, the secreted protein is a cellulase.
  • the secreted protein is encoded by a gene selected from NCU07340, NCU09680, NCU07898, NCU00762, NCU08760, NCU05057, NCU02240, NCU07190, NCU07898, NCU08760, NCU00206, NCU07143, NCU09491, NCU09664, NCU05598, NCU09764, and NCU05137.
  • the inactivating mutations are deletions.
  • the cell is a recombinant cell.
  • the cell is a fungal or yeast cell. In certain embodiments that may be combined with any of the preceding embodiments, the cell is a filamentous fungus of the ascomycete or basidiomycete species. In certain embodiments that may be combined with any of the preceding embodiments, the cell is selected from Neurospora crassa ( N.
  • Aspergillus nidulans cells Trichoderma reesei cells, Phanerochaete chrysosporium cells, Sporotrichum thermophile ( Myceliophthora thermophila ) cells, Gibberella zeae cells, Sclerotinia sclerotiorum cells, Botryotinia fuceliana cells, Aspergillus niger cells, Penicillium chrysogenum cells, Schizophyllum commune cells, Postia placenta cells, Aspergillus oryzae cells, and Acremonium cellulolyticus cells.
  • the two or more ⁇ -glucosidase genes are three or more ⁇ -glucosidase genes. In certain embodiments that may be combined with any of the preceding embodiments, the two or more ⁇ -glucosidase genes are four or more ⁇ -glucosidase genes. In certain embodiments that may be combined with any of the preceding embodiments, the two or more ⁇ -glucosidase genes are five or more ⁇ -glucosidase genes. In certain embodiments that may be combined with any of the preceding embodiments, the two or more ⁇ -glucosidase genes are six or more ⁇ -glucosidase genes.
  • the two or more ⁇ -glucosidase genes are seven or more ⁇ -glucosidase genes.
  • the three or more ⁇ -glucosidase genes, four or more ⁇ -glucosidase genes, five or more ⁇ -glucosidase genes, six or more ⁇ -glucosidase genes, or seven or more ⁇ -glucosidase genes include NCU00130, NCU04952, and NCU08755.
  • At least one of the ⁇ -glucosidase genes encodes an intracellular ⁇ -glucosidase. In certain embodiments that may be combined with any of the preceding embodiments, at least one of the ⁇ -glucosidase genes encodes an extracellular ⁇ -glucosidase. In certain embodiments that may be combined with any of the preceding embodiments, the at least one ⁇ -mannosidase gene is NCU00890. In certain embodiments that may be combined with any of the preceding embodiments, the at least one phospholipase gene or phospholipase-like gene is NCU06650.
  • Another aspect of the present disclosure provides a recombinant cell exhibiting reduced expression of at least two ⁇ -glucosidase genes compared to the expression of the at least two ⁇ -glucosidase genes in a corresponding non-recombinant cell, where the expression is reduced by siRNA, antisense DNA, quelling, or meiotic silencing, and where cellulosic biomass induces the cell to secrete higher levels of a protein than the corresponding non-recombinant cell in which the expression of the at least two ⁇ -glucosidase genes is not reduced.
  • the cell further exhibits reduced expression of a cre-1 gene compared to the expression of the cre-1 gene in a corresponding non-recombinant cell, where the expression is reduced by siRNA, antisense DNA, quelling, or meiotic silencing, and where cellulosic biomass induces the cell to secrete higher levels of a protein than the corresponding non-recombinant cell in which the expression of the cre-1 gene is not reduced.
  • the function of creA/cre-1 is reduced by overexpression of a dominant negative mutant or a protein inhibitor, where cellulosic biomass induces the cell to secrete higher levels of a protein than a corresponding cell in which the dominant negative mutant is not overexpressed.
  • the cell further exhibits reduced expression of at least one ⁇ -mannosidase gene compared to the expression of the at least one ⁇ -mannosidase gene in a corresponding non-recombinant cell, where expression is reduced by siRNA, antisense DNA, quelling, or meiotic silencing, and where cellulosic biomass induces the cell to secrete higher levels of a protein than the corresponding non-recombinant cell in which the expression of the least one ⁇ -mannosidase gene is not reduced.
  • the cell further exhibits reduced expression of at least one phospholipase gene or phospholipase-like gene compared to the expression of the at least one phospholipase gene or phospholipase-like gene in a corresponding non-recombinant cell, where expression is reduced by siRNA, antisense DNA, quelling, or meiotic silencing, and where cellulosic biomass induces the cell to secrete higher levels of a protein than the non-recombinant cell in which the expression of the least one phospholipase gene or phospholipase-like gene is not reduced.
  • the cellulosic biomass includes one or more of a polysaccharide, an oligosaccharide, cellulose, microcrystalline cellulose, cellodextrin, cellobiose, cellotriose, cellotetraose, cellopentose, and cellohexose.
  • the cellulosic biomass includes cellobiose.
  • Another aspect of the present disclosure provides a recombinant cell exhibiting reduced expression of at least two ⁇ -glucosidase genes compared to the expression of the at least two ⁇ -glucosidase genes in a corresponding non-recombinant cell, where the expression is reduced by siRNA, antisense DNA, quelling, or meiotic silencing, and where a saccharide induces the cell to secrete higher levels of a protein than the corresponding non-recombinant cell in which the expression of the at least two ⁇ -glucosidase genes is not reduced.
  • the cell further exhibits reduced expression of a cre-1 gene compared to the expression of the cre-1 gene in a corresponding non-recombinant cell, where the expression is reduced by siRNA, antisense DNA, quelling, or meiotic silencing, and where a saccharide induces the cell to secrete higher levels of a protein than the corresponding non-recombinant cell in which the expression of the cre-1 gene is not reduced.
  • the function of creA/cre-1 is reduced by overexpression of a dominant negative mutant or a protein inhibitor, where a saccharide induces the cell to secrete higher levels of a protein than a corresponding cell in which the dominant negative mutant is not overexpressed.
  • the cell further exhibits reduced expression of at least one ⁇ -mannosidase gene compared to the expression of the at least one ⁇ -mannosidase gene in a corresponding non-recombinant cell, where expression is reduced by siRNA, antisense DNA, quelling, or meiotic silencing, and where a saccharide induces the cell to secrete higher levels of a protein than the corresponding non-recombinant cell in which the expression of the least one ⁇ -mannosidase gene is not reduced.
  • the cell further exhibits reduced expression of at least one phospholipase gene or phospholipase-like gene compared to the expression of the at least one phospholipase gene or phospholipase-like gene in a corresponding non-recombinant cell, where expression is reduced by siRNA, antisense DNA, quelling, or meiotic silencing, and where a saccharide induces the cell to secrete higher levels of a protein than the non-recombinant cell in which the expression of the least one phospholipase gene or phospholipase-like gene is not reduced.
  • the saccharide is selected from a polysaccharide, an oligosaccharide, cellulose, microcrystalline cellulose, cellodextrin, cellobiose, cellotriose, cellotetraose, cellopentose, and cellohexose. In certain embodiments that may be combined with any of the preceding embodiments, the saccharide is cellobiose.
  • the secreted protein is a cellulose-induced protein. In certain embodiments that may be combined with any of the preceding embodiments, the secreted protein is selected from a cellulase, a GH61 enzyme, a cellobiose dehydrogenase, a lactonase, a carbohydrate esterase, a polysaccharide lyase, and a cellulose binding domain-containing protein, and combinations thereof. In certain embodiments that may be combined with any of the preceding embodiments, the secreted protein is a cellulase.
  • the secreted protein is encoded by a gene selected from NCU07340, NCU09680, NCU07898, NCU00762, NCU08760, NCU05057, NCU02240, NCU07190, NCU07898, NCU08760, NCU00206, NCU07143, NCU09491, NCU09664, NCU05598, NCU09764, and NCU05137.
  • the two or more ⁇ -glucosidase genes are three or more ⁇ -glucosidase genes.
  • the two or more ⁇ -glucosidase genes are four or more ⁇ -glucosidase genes. In certain embodiments that may be combined with any of the preceding embodiments, the two or more ⁇ -glucosidase genes are five or more ⁇ -glucosidase genes. In certain embodiments that may be combined with any of the preceding embodiments, the two or more ⁇ -glucosidase genes are six or more ⁇ -glucosidase genes. In certain embodiments that may be combined with any of the preceding embodiments, the two or more ⁇ -glucosidase genes are seven or more ⁇ -glucosidase genes.
  • the three or more ⁇ -glucosidase genes, four or more ⁇ -glucosidase genes, five or more ⁇ -glucosidase genes, six or more ⁇ -glucosidase genes, or seven or more ⁇ -glucosidase genes include NCU00130, NCU04952, and NCU08755.
  • at least one of the ⁇ -glucosidase genes encodes an intracellular ⁇ -glucosidase.
  • At least one of the ⁇ -glucosidase genes encodes an extracellular ⁇ -glucosidase.
  • the at least one ⁇ -mannosidase gene is NCU00890.
  • the at least one phospholipase gene or phospholipase-like gene is NCU06650.
  • the cell is a stable cell line or a transiently transfected cell.
  • the cell is a fungal or yeast cell.
  • the cell is a filamentous fungus of the ascomycete or basidiomycete species. In certain embodiments that may be combined with any of the preceding embodiments, the cell is selected from Neurospora crassa ( N.
  • Aspergillus nidulans cells Trichoderma reesei cells, Phanerochaete chrysosporium cells, Sporotrichum thermophile ( Myceliophthora thermophila ) cells, Gibberella zeae cells, Sclerotinia sclerotiorum cells, Botryotinia fuceliana cells, Aspergillus niger cells, Penicillium chrysogenum cells, Schizophyllum commune cells, Postia placenta cells, Aspergillus oryzae cells, and Acremonium cellulolyticus cells.
  • Another aspect of the present disclosure relates to a method for the degradation of biomass, by: (a) providing lignocellulosic biomass; (b) providing the cell of any of the preceding embodiments, or a cell containing an inactivating mutation in the cre-1 gene; (c) inducing the cell to secrete a protein by contacting the cell with a cellulosic biomass; and (d) contacting the induced cell with the lignocellulosic biomass, where the secreted protein degrades the lignocellulosic biomass.
  • the cellulosic biomass includes one or more of a polysaccharide, an oligosaccharide, cellulose, microcrystalline cellulose, cellodextrin, cellobiose, cellotriose, cellotetraose, cellopentose, and cellohexose.
  • the cellulosic biomass includes cellobiose.
  • Another aspect of the present disclosure relates to a method for the degradation of biomass, by: (a) providing lignocellulosic biomass; (b) providing the cell of any of the preceding embodiments, or a cell containing an inactivating mutation in the cre-1 gene; (c) inducing said cell to secrete a protein by contacting the cell with a saccharide; and (d) contacting the induced cell with the lignocellulosic biomass, where the secreted protein degrades the lignocellulosic biomass.
  • the saccharide is selected from a polysaccharide, an oligosaccharide, cellulose, microcrystalline cellulose, cellodextrin, cellobiose, cellotriose, cellotetraose, cellopentose, and cellohexose.
  • the saccharide is cellobiose.
  • the secreted protein is a cellulose-induced protein.
  • the secreted protein is selected from a cellulase, a GH61 enzyme, a cellobiose dehydrogenase, a lactonase, a carbohydrate esterase, a polysaccharide lyase, and a cellulose binding domain-containing protein, and combinations thereof.
  • the secreted protein is a cellulase.
  • the secreted protein is encoded by a gene selected from NCU07340, NCU09680, NCU07898, NCU00762, NCU08760, NCU05057, NCU02240, NCU07190, NCU07898, NCU08760, NCU00206, NCU07143, NCU09491, NCU09664, NCU05598, NCU09764, and NCU05137.
  • FIG. 1 shows a model for transcriptional regulation of cellulases in ⁇ -glucosidase deletion strains of N. crassa . Both transcriptional de-repression and specific induction are required to achieve maximal transcriptional activation of cellulase gene expression. Arrows indicate possible pathways for cellulose metabolites. Blue lines indicate pathways believed to be minimized in the ⁇ 3 ⁇ G and ⁇ 3 ⁇ G ⁇ cre deletion strains; and red lines indicate pathways believed to be most active in the ⁇ 3 ⁇ G and ⁇ 3 ⁇ G ⁇ cre deletion strains.
  • FIG. 2 shows gene expression time courses for cellulase enzymes in N. crassa .
  • FIG. 2A shows the cellobiohydrolase I (cbh-1, NCU07340) time course.
  • FIG. 2B shows the endoglucanase 2 (gh5-1, NCU00762) time course. Expression levels for all genes were normalized to 1 when induced with 2% sucrose. Strains were grown in minimal media with 2% sucrose for 16 hours followed by 4 hours growth in minimal media with 2% Avicel®. Actin (NCU04173) gene expression levels were used as an endogenous control in all samples. Each reaction was done in triplicate and error bars indicate a 95% confidence interval.
  • FIG. 3 shows gene expression of select cellulases after 4 hours induction with 0.2% cellobiose or 1% Avicel® in WT, ⁇ 3 ⁇ G and ⁇ 3 ⁇ G ⁇ cre.
  • Gene expression levels of cbh-1, gh6-2, and gh5-1 were normalized to 1 when induced with 1% sucrose. Actin was used as an endogenous control in all samples. Each strain was grown in triplicate and error bars indicate 1 standard deviation.
  • FIG. 4 shows gene expression levels of cellulases cellobiohydrolase I (cbh-1, NCU07340) and endoglucanase 2 (gh5-1, NCU00762) in ⁇ cre-1 at 4 hrs post transfer to minimal media with 2% sucrose. Expression levels for both genes were normalized to 1 for wild type induction with 2% sucrose. Actin (NCU04173) gene expression levels were used as an endogenous control. Each reaction was done in triplicate and error bars indicate a 95% confidence interval.
  • FIG. 5 shows gene expression levels of cellulases cellobiohydrolase I (cbh-1, NCU07340) and endoglucanase 2 (gh5-1, NCU00762) under starvation conditions in wild type (WT), ⁇ cre-1, ⁇ 4952 ⁇ 8755 ⁇ 130, and ⁇ 4952 ⁇ 8755 ⁇ 130 ⁇ cre-1.
  • Expression levels for all genes were normalized to 1 when induced with 2% sucrose. Strains were grown in minimal media with 2% sucrose for 16 hrs followed by 4 hrs growth in minimal media with no carbon source added. Actin (NCU04173) gene expression levels were used as an endogenous control in all samples. Each reaction was done in triplicates and error bars indicate a 95% confidence interval.
  • FIG. 6 shows gene expression levels of cellulases cellobiohydrolase I (cbh-1, NCU07340) and endoglucanase 2 (gh5-1, NCU00762) after 4 hour induction with either 10 mM or 1 mM cellobiose.
  • FIG. 6A shows results for the wild type.
  • FIG. 6B shows results for the ⁇ 4952 ⁇ 8755 ⁇ 130 deletion mutant.
  • FIG. 6C shows results for ⁇ 4952 ⁇ 8755 ⁇ 130 ⁇ cre-1 deletion mutant. Expression levels for all genes were normalized to 1 when induced with 2% sucrose.
  • FIG. 7 summarizes protein production and enzyme activity in WT, ⁇ 3 ⁇ G, and ⁇ 3 ⁇ G ⁇ cre strains after induction with cellobiose or Avicel®.
  • FIG. 7A shows the production of cellulases in a bioreactor using ⁇ 3 ⁇ G induced with cellobiose.
  • FIG. 7B shows the production of cellulases in a bioreactor using ⁇ 3 ⁇ G ⁇ cre induced with cellobiose.
  • FIG. 7C shows the production of cellulases in a bioreactor using WT induced with cellobiose.
  • FIG. 7D shows the production of cellulases in a bioreactor using WT grown 5 days on Avicel®.
  • FIG. 7E shows 24-hour induced supernatant activity from 7 A, 7 B, and 7 D towards Avicel®.
  • FIG. 7F shows Azo-CMC (endoglucanase) activity time course from bioreactor culture supernatants in 7 A and 7 B. Azo-CMC activity is expressed as a percentage of activity from WT culture supernatant grown on 2% Avicel® for 5 days.
  • FIG. 8 compares MuLac activities (cellobiohydrolase I) in culture filtrates from wild type (WT), ⁇ cre-1, ⁇ 4952 ⁇ 8755 ⁇ 130, and ⁇ 4952 ⁇ 8755 ⁇ 130 ⁇ cre-1.
  • FIG. 8A shows MuLac activity expressed as a percentage of the wild type activity on Avicel® after 4 days on Avicel®.
  • FIG. 8B shows MuLac activity expressed as ⁇ g purified recombinant Cbh-1 equivalents. Strains were grown in 2% sucrose for 16 hrs followed by 4 days in 2% sucrose, 2% cellobiose, or 2% Avicel® with time points taken at both 2 and 4 days. Exoglucanase activity in the culture supernatant was measured using a 4-Methylumbelliferyl- ⁇ -D-cellobioside (MuLac) assay.
  • MoLac 4-Methylumbelliferyl- ⁇ -D-cellobioside
  • FIG. 9 compares Azo-CM-cellulose (endo-1,4-( ⁇ -glucanase) activities in culture filtrates from wild type (WT), ⁇ cre-1, ⁇ 4952 ⁇ 8755 ⁇ 130, and ⁇ 4952 ⁇ 8755 ⁇ 130 ⁇ cre-1. Strains were grown in 1% sucrose for 24 hrs followed by 4 days 2% sucrose, 1% Avicel®, or 2% cellobiose. The endo-1,4- ⁇ -glucanase activity is presented as a percentage of the wild type activity on Avicel® after 4 days and of activity. Note: No data is shown for sucrose cultures because Azo-CM-cellulose activity was not detectable for any of the 4 strains.
  • FIG. 10 compares the phenotypes of N. crassa wild type (WT) and ⁇ cre-1 strains.
  • FIG. 10A shows an SDS-PAGE analysis of secreted proteins in culture filtrates from WT and ⁇ cre-1 strains grown on Avicel® for 7 days. Protein bands representing ⁇ -glucosidase (NCU04952), cellobiohydrolase 1 (cbh-1, NCU07340) and 2 (cbh-2, NCU09680), and endoglucanase 2 (gh5-1, NCU00762) are marked.
  • FIG. 10B compares the endoglucanase activity on Azo-CMC, protein concentrations, and glucose and cellobiose concentrations as determined by Avicelase assays of 7-day culture supernatants from WT and ⁇ cre-1 strains.
  • FIG. 11 shows a SDS-PAGE analysis of secreted proteins in culture filtrates from wild type (WT), ⁇ cre-1, ⁇ 4952 ⁇ 8755 ⁇ 130, and ⁇ 4952 ⁇ 8755 ⁇ 130 ⁇ cre-1 deletion mutants.
  • Strains were grown in 1% sucrose for 24 hours followed by 4 days in 2% sucrose, 2% cellobiose, 1% sucrose and 1% cellobiose, or 1% sucrose and 1% Avicel® with samples taken at 24 hour time points.
  • 15 ⁇ l filtered culture supernatant was run on a Criterion 10% Tris-HCl polyacrylamide gel and stained with Thermo Scientific GelCode Blue Stain Reagent.
  • the protein running at 72 kDa in ⁇ cre-1 and ⁇ 4952 ⁇ 8755 ⁇ 130 ⁇ cre-1 on sucrose has been identified using Mass Spectrometry as NCU01517 (Glucoamylase 1).
  • FIG. 12 shows a SDS-PAGE analysis of secreted proteins in culture filtrates from wild type N. crassa and ⁇ 4952 ⁇ 8755 ⁇ 130 ( ⁇ -G tKO). Strains were grown in 1% sucrose for 24 hrs followed by 5 days in 2% sucrose, 2% cellobiose, or 2% Avicel®. Protein bands representing cellobiohydrolase 1 (cbh-1, NCU07340), cellobiohydrolase 2 (cbh-2, NCU09680), and endoglucanase 2 (gh5-2, NCU00762) are marked. In addition, ⁇ -glucosidase (NCU04952) is marked in the wild type and its absence is outlined in the triple deletion ⁇ 4952 ⁇ 8755 ⁇ 130.
  • cbh-1, NCU07340 Protein bands representing cellobiohydrolase 1 (cbh-1, NCU07340), cellobiohydrolase 2 (cbh-2, NCU09680), and endoglucanase
  • FIG. 13 shows ClustalW alignments for NCU00130 (SEQ ID NO: 1), NCU04952 (SEQ ID NO: 2), and NCU08755 (SEQ ID NO: 3) orthologues in closely related fungi.
  • the entire sequence is provided for the N. crassa gene with orthologues displaying only divergent amino acids.
  • a “.” indicates an identical residue and “-” indicates an insertion or deletion.
  • FIG. 14 shows the evolutionary relationships of ⁇ -glucosidase NCU00130 orthologues.
  • the evolutionary history was inferred using the Neighbor-Joining method (Saitou N. and Nei M., 1987).
  • the tree is drawn to scale, with branch lengths in the same units as those of the evolutionary distances used to infer the phylogenetic tree.
  • the evolutionary distances were computed using the Poisson correction method (Zuckerkandl E. and Pauling L., 1965) and are in the units of the number of amino acid substitutions per site.
  • the analysis involved 11 amino acid sequences. All positions containing gaps and missing data were eliminated. There were a total of 447 positions in the final dataset. Evolutionary analyses were conducted in MEGA5 (Tamura K, Dudley J., Nei M., and Kumar S., 2007).
  • FIG. 15 shows the evolutionary relationships of ⁇ -glucosidase NCU04952 orthologues.
  • the analysis involved 11 amino acid sequences. There were a total of 690 positions in the final dataset.
  • FIG. 16 shows the evolutionary relationships of ⁇ -glucosidase NCU08755 orthologues.
  • the analysis involved 11 amino acid sequences. There were a total of 709 positions in the final dataset.
  • FIG. 17 shows cellulase induction in WT and ⁇ 3 ⁇ G after induction with cellodextrins.
  • FIG. 17A shows cbh-1, gh5-1, and gh6-2 expression in WT after a 4-hour induction with Avicel®, cellobiose, cellotriose, or cellotetraose.
  • FIG. 17B shows cbh-1, gh5-1, and gh6-2 expression in ⁇ 3 ⁇ G after a 4-hour induction with Avicel®, cellobiose, cellotriose, or cellotetraose.
  • Gene expression levels of cbh-1, gh5-1 and gh6-2 were normalized to 1 when induced with 1% sucrose. Actin (NCU04173) gene expression levels were used as an endogenous control in all samples. Error bars indicate 1 standard deviation.
  • FIG. 18 shows cellulase expression levels in WT and ⁇ -glucosidase deletion strains after induction with cellobiose or Avicel®.
  • FIG. 18A shows an SDS-PAGE analysis of secreted proteins in culture filtrates from WT, ⁇ 3 ⁇ G, and ⁇ 3 ⁇ G ⁇ cre strains. Protein bands representing CBH-1, GH6-2, and GH5-1 are marked. In addition, the absence of the extracellular ⁇ -glucosidase (NCU04952) is marked in the triple knockout. The presence of glucoamylase I (NCU01517) correlates with the deletion of the cre-1 gene. Cultures were grown in 1% sucrose for 24 hours followed by the addition of 2% sucrose or 0.2% cellobiose.
  • Supernatant was harvested after 24 hours (WT, ⁇ 3 ⁇ G and ⁇ 3 ⁇ G ⁇ cre) or 72 hours ( ⁇ 3 ⁇ G).
  • the WT Avicel® culture was grown for 5 days on 2% Avicel®, ⁇ 3 ⁇ G was grown in 1% sucrose for 24 hours followed by 48 hours in 1% Avicel® and ⁇ 3 ⁇ G ⁇ cre was grown in 1% sucrose for 24 hours followed by 24 hours in 1% Avicel®.
  • FIG. 18B shows activity of supernatant from 18 A towards Avicel®. Glucose (dark grey) and cellobiose (light grey) were measured after 24 hours of incubation with 1% Avicel® at 50° C. Error bars are 1 standard deviation.
  • FIG. 19 shows cellulase induction in WT and ⁇ 3 ⁇ G after induction with sophorose, lactose or D-(+)-galactose.
  • FIG. 19A shows cbh-1 expression in WT and ⁇ 3 ⁇ G after a 4 hour induction with 1 mM sophorose, 1 mM lactose or 1 mM D-(+)-galactose.
  • FIG. 19B shows gh6-2 expression in WT and ⁇ 3 ⁇ G after a 4 hour induction with 1 mM sophorose, 1 mM lactose or 1 mM D-(+)-galactose.
  • Gene expression levels of cbh-1 and gh6-2 were normalized to 1 when induced with 1% sucrose. Actin (NCU04173) gene expression levels were used as an endogenous control in all samples. Error bars indicate 1 standard deviation.
  • FIG. 20 shows RNA sequencing of the WT and ⁇ 3 ⁇ G strains.
  • FIG. 20A shows hierarchical clustering analysis of 318 genes differentially induced in WT N. crassa by Avicel®, compared to induction by cellobiose. Light color indicates higher relative expression and dark color indicates lower relative expression.
  • FIG. 20B shows cellulase expression in FPKMs (fragments per kilobase of exon per million fragments mapped) for the WT induced with cellobiose or Avicel® compared to ⁇ 3 ⁇ G induced with cellobiose. All strains were grown for 16 hours on 2% sucrose, followed by a transfer to no carbon source (Vogels salt solution only), 0.2% cellobiose or 1% Avicel® for 4 hours.
  • FIG. 21 shows enzyme activity in WT, ⁇ 3 ⁇ G, and ⁇ 3 ⁇ G ⁇ cre strains after induction with cellobiose or Avicel®.
  • FIG. 21A shows the 24-hour induced supernatant activity towards Avicel®. Cellulase activity of culture supernatant from ⁇ 3 ⁇ G (square) and ⁇ 3 ⁇ G ⁇ cre (diamond) strains when induced with cellobiose for 24 hours compared to culture supernatants from WT grown on Avicel® for 5 days (triangle).
  • FIG. 21B shows breakdown of cellobiose (light grey) and glucose (dark grey) produced in the Avicel® hydrolysis assay (from A) after 36 hours. Error bars are 1 standard deviation.
  • FIG. 22 summarizes the proteins identified by Mass Spectrometry in wild type (Avicel®), ⁇ 3 ⁇ G (cellobiose), and ⁇ 3 ⁇ G ⁇ cre (cellobiose) Neurospora crassa strains.
  • FIG. 23 compares MuLac activity (cellulase activity) in culture filtrates from Neurospora crassa strains ⁇ 3 ⁇ G, ⁇ 3 ⁇ G ⁇ cre, ⁇ 3 ⁇ G ⁇ 890, ⁇ 3 ⁇ G ⁇ 6650, ⁇ 3 ⁇ G ⁇ 6650 ⁇ 890, ⁇ 3 ⁇ G ⁇ cre ⁇ 6650, ⁇ 3 ⁇ G ⁇ cre ⁇ 890, and ⁇ 3 ⁇ G ⁇ cre ⁇ 6650 ⁇ 890.
  • the strains with ⁇ 890 have a deletion in the ⁇ -mannosidase gene NCU00890.
  • the strains with ⁇ 6650 have a deletion in the phospholipase gene or phospholipase-like gene NCU06650.
  • mutant cells and recombinant cells that exhibit increased secretion of a protein, such as a cellulase, in response to induction by cellulosic biomass or a saccharide; and to methods of using such cells to increase secretion of a protein.
  • the secreted proteins may find use in degrading lignocellulosic biomass.
  • mutant cells of the present disclosure contain inactivating mutations in at least one gene, such as a ⁇ -glucosidase gene, a cre-1 gene, a ⁇ -mannosidase gene, or a phospholipase or phospholipase-like gene.
  • recombinant cells of the present disclosure exhibit reduced expression of at least one gene, such as a ⁇ -glucosidase gene, a cre-1 gene, a ⁇ -mannosidase gene, or a phospholipase or phospholipase-like gene, compared to the expression of the at least one gene in a corresponding non-recombinant cell.
  • at least one gene such as a ⁇ -glucosidase gene, a cre-1 gene, a ⁇ -mannosidase gene, or a phospholipase or phospholipase-like gene
  • Cellulosic biomass is mass obtained from living matter, such as plants, algae, fungi, bacteria, and bacterial biofilms that contains polysaccharides and polysaccharide components.
  • Cellulose is the predominant polysaccharide in cellulosic biomass.
  • Cellulose is a homopolymer of anhydrocellobiose (a linear beta-(1-4)-D-glucan), and includes glucose units linked together in ⁇ -1,4-glycosidic linkages. Although generally polymorphous, cellulose is found in plant tissue primarily as an insoluble crystalline matrix of parallel glucan chains.
  • Cellulosic biomass may be raw biomass, pre-treated biomass, or processed biomass.
  • Cellulosic biomass may also include one or more saccharides.
  • Suitable cellulosic biomass of the present disclosure may include, without limitation, saccharides, polysaccharides, oligosaccharides, purified cellulose, and cellulose derivatives.
  • Purified celluloses include holocelluloses, such as Solka Flok, and microcrystalline celluloses, such as Avicel® and Sigmacell®.
  • Cellulose derivatives include, without limitation, cellodextrins, ⁇ -methylumbelliferyl-oligosaccharides, p-nitrophenol-oligosaccharides, long chain cellulose derivatives, carboxymethyl cellulose (CMC), and hydroxyethyl cellulose (HEC).
  • cellodextrin(s) refers to a ⁇ (1 ⁇ 4) glucose polymers of varying length and includes, without limitation, cellobiose (2 glucose monomers), cellotriose (3 glucose monomers), cellotetraose (4 glucose monomers), cellopentose (5 glucose monomers), and cellohexose (6 glucose monomers).
  • cellobiose 2 glucose monomers
  • cellotriose 3 glucose monomers
  • cellotetraose (4 glucose monomers)
  • cellopentose (5 glucose monomers)
  • cellohexose (6 glucose monomers).
  • short-chain cellodextrins such as cellobiose are soluble.
  • secreted proteins of the present disclosure do not adhere to short-chain cellodextrins, such as cellobiose.
  • cellulosic biomass of the present disclosure may be raw biomass material that is degraded by the cells of the present disclosure.
  • the degraded biomass may include, without limitation, polysaccharides, such as cellulose and microcrystalline cellulose; or oligosaccharides, such as cellodextrin and cellobiose.
  • cellulosic biomass of the present disclosure may include purified polysaccharides, such as cellulose and microcrystalline cellulose; or oligosaccharides, such as cellodextrin and cellobiose.
  • biomass of the present disclosure may include a mixture of polysaccharides, such as cellulose and microcrystalline cellulose; and oligosaccharides, such as cellodextrin and cellobiose.
  • cellulosic biomass of the present disclosure is directly added to mutant cells or recombinant cells of the present disclosure to induce secretion of a protein.
  • secretion of a protein is induced from mutant cells or recombinant cells of the present disclosure by one or more cellulose derivatives, such as cellodextrin or cellobiose, that are generated in situ by the cells via degradation of the cellulosic biomass.
  • cellulose derivatives such as cellodextrin or cellobiose
  • a sufficient amount of the cellulosic biomass to generate cellulose derivatives that induce secretion from the cell but that does not adhere to or otherwise sequester the one or more types of proteins secreted from the cell.
  • saccharides may be used to induce secretion of a protein from a mutant cell or recombinant cell of the present disclosure.
  • Suitable saccharides include, without limitation, polysaccharides, oligosaccharides, sophorose, cellulose, microcrystalline cellulose, cellodextrin, cellobiose, cellotriose, cellotetraose, cellopentose, and cellohexose.
  • mutant cells and recombinant cells of the present disclosure exhibit increased secretion of at least one, at least two, at least three, at least four, at least five, or more types of proteins in response to induction by cellulosic biomass or a saccharide.
  • increased secretion refers to increased levels of secretion of a protein of the present disclosure.
  • Secretion involves the movement of the protein from inside the cell to outside of the cell.
  • the increased levels of secretion may be the result of increasing expression or production of the protein of interest.
  • the increased levels of secretion may be the result of increasing transport of the protein of interest from the cell.
  • the methods of the present disclosure may also increase level of secretion of a protein by altering a pathway involved in the production and secretion of a protein that results in overall increased levels of secretion of the protein.
  • Types of proteins of the present disclosure that may be secreted include, without limitation, endogenous proteins and heterologous proteins.
  • Endogenous proteins of the present disclosure are proteins endogenous to a cell of the present disclosure, or naturally produced by a cell of the present disclosure.
  • Heterologous proteins of the present disclosure are proteins that are not normally expressed in a cell of the present disclosure.
  • Heterologous proteins may be recombinantly expressed in the cell by any method known in the art.
  • the recombinant nucleic acid encoding a heterologous protein is operably linked to a regulatory sequence, such as a promoter. Any suitable regulatory sequence known in the art may be used. Suitable promoters include, without limitation, constitutive promoters or inducible promoters.
  • the heterologous protein may contain a secretion peptide that directs its secretion from the cell. Any secretion peptide known in the art suitable for use in the methods of the present disclosure may be used.
  • the secreted protein is a cellulose-induced protein.
  • cellulose-induced protein refers to a protein whose expression and secretion in a wild-type cell (e.g., non-mutant or non-recombinant cell) is induced by cellulose.
  • cellulose-induced proteins are described in C. M. Phillips et al., 2011 (Phillips, C M et al., Proteome Res. 2011 Sep. 2; 10(9):4177-85. Epub 2011 Aug. 1).
  • Secreted cellulose-induced proteins of the present disclosure include, without limitation, cellulases, GH61 enzymes, cellobiose dehydrogenases, lactonases, carbohydrate esterases, polysaccharide lyases, and cellulose binding domain-containing proteins.
  • a “cellulase” or “cellulase polypeptide” refers to a polypeptide having enzymatic activity that catalyzes the hydrolysis of cellulose, lichenin, and cereal ⁇ -D-glucans.
  • cellulases may have hydrolyze 1,4- ⁇ -D-glucosidic linkages in cellulose.
  • Ccellulases of the present disclosure include, without limitation, endocellulases, endoglucanases, endo-1,4- ⁇ -glucanases, endo-1,4- ⁇ -D-glucanases, carboxymethyl cellulases (CMCases), ⁇ -1,4-glucanases, ⁇ -1,4-endoglucan hydrolases, and celludextrinases; exocellulases, such as exoglucanases; cellobiases; cellobiohydrolases; oxidative cellulases, such as cellobiose dehydrogenases; and cellulose phosphorylases.
  • GH61 enzyme(s) refers to Glycoside Hydrolase Family 61 enzymes.
  • GH61 enzymes of the present disclosure are capable of enhancing cellulase activity.
  • examples of GH61 enzymes include, without limitation, polysaccharide monooxygenases.
  • a GH61 hydrolase of the present disclosure is encoded by a GH61-1 gene, a GH61-2 gene, a GH61-5 gene, the NCU07898 gene, the NCU08760 gene, homologues thereof, and orthologues thereof.
  • Cellobiose dehydrogenases are enzymes with oxidoreductase activity, and include enzymes having EC 1.1.99.18 activity.
  • a cellobiose dehydrogenase of the present disclosure is encoded by NCU00206, the cdh-1 gene, homologues thereof, and orthologues thereof.
  • Lactonases are enzymes that can hydrolyze the ester bond of the homoserine lactone ring of acylated homoserine lactones.
  • a lactonase of the present disclosure is encoded by NCU07143, the lac-2 gene, homologues thereof, and orthologues thereof.
  • Carbohydrate esterases are enzymes that have EC 3.1.1.- and EC 3.1.2-activity.
  • Examples of carbohydrate esterases include, without limitation, acetyl xylan esterases, cinnamoyl esterases, feruloyl esterases, carboxylesterases, and S-formylglutathione hydrolases.
  • a carbohydrate esterase of the present disclosure is encoded by NCU09491, NCU09664, homologues thereof, and orthologues thereof.
  • Polysaccharide lyases are enzymes that have EC 4.2.2-activity.
  • a polysaccharide lyase of the present disclosure is encoded by NCU05598, homologues thereof, and orthologues thereof.
  • cellulose binding domain-containing protein(s) refers to a protein that contains a cellulose binding domain.
  • a cellulose binding domain is a protein domain found in cellulose-active enzymes, such as glycoside hydrolases. Generally, cellulose binding domains have carbohydrate-binding activity.
  • a cellulose binding domain-containing protein of the present disclosure is encoded by NCU09764, homologues thereof, and orthologues thereof.
  • a secreted cellulose-induced protein of the present disclosure is a protein encoded by NCU05137, homologues thereof, and orthologues thereof.
  • mutant cells of the present disclosure contain inactivating mutations in at least one gene.
  • suitable inactivating mutations include, without limitation, deletions, point mutations, loss-of-function mutations, truncations, duplications, amplifications, translocations, and/or inversions that result inhibit the function of the protein encoded by the gene.
  • Methods of generating one or more inactivating mutations in a gene of interest are well known in the art and include, without limitation, PCR mutagenesis, insertional mutagenesis, chemical mutagenesis, and irradiation.
  • the mutant cells are fungal or yeast cells.
  • the mutant cells may be ascomycete basidiomycete fungal cells, Neurospora crassa ( N. crassa ) cells, Aspergillus nidulans cells, Trichoderma reesei cells, Phanerochaete chrysosporium cells, Sporotrichum thermophile ( Myceliophthora thermophila ) cells, Gibberella zeae cells, Sclerotinia sclerotiorum cells, Botryotinia fuceliana cells, Aspergillus niger cells, Penicillium chrysogenum cells, Schizophyllum commune cells, Postia placenta cells, Aspergillus oryzae cells, or Acremonium cellulolyticus cells.
  • the mutant cells are mutant N. crassa cells.
  • the mutant cells are recombinant cells.
  • the mutant, recombinant cells are N. crassa mutant, recombinant cells.
  • ⁇ -Glucosidase genes encode ⁇ -glucosidase enzymes.
  • ⁇ -glucosidase(s) refers to a ⁇ -D-glucoside glucohydrolase that catalyzes the hydrolysis of terminal non-reducing ⁇ -D-glucose residues with the release of glucose.
  • ⁇ -Glucosidases are highly conserved enzymes.
  • a mutant cell of the present disclosure contains inactivating mutations in at least two ⁇ -glucosidase genes, which cause a loss of the ⁇ -glucosidase function encoded by the at least two genes.
  • Inactivating mutations of the at least two ⁇ -glucosidase genes include, without limitation, deletion mutations, point mutations, nonsense mutations, truncations, and insertions.
  • Inactivating mutations may completely abolish ⁇ -glucosidase activity or inhibit ⁇ -glucosidase activity by at least 75%, at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or more.
  • Inactivating mutations may affect the expression levels of mutated genes or affect the functional activity of proteins or RNAs encoded by mutated genes. Inactivating mutations may also be cis- or trans-acting. Inactivating mutations may be introduced by random mutagenesis, including irradiation or exposure to mutagenic chemicals, or they may be introduced in a targeted manner, including homologous recombination and crossing of strains that include inactivating mutations.
  • ⁇ -Glucosidases of the present disclosure that contain inactivating mutations may be intracellular ⁇ -glucosidases or extracellular (i.e., secreted) ⁇ -glucosidases.
  • suitable ⁇ -glucosidases containing inactivating mutations include, without limitation, those encoded by the N. crassa genes NCU00130, NCU04952, NCU08755, homologues thereof, and orthologues thereof.
  • Examples of NCU00130 orthologues, NCU04952 orthologues, and NCU08755 orthologues include, without limitation, those listed in FIGS. 13-16 .
  • cellulosic biomass or a saccharide may induce the mutant cell to transcribe 10, 50, 100, 500, 1,000, 5,000, 10,000, 50,000 or 100,000-fold higher levels of at least one type of protein compared to that of a cell lacking the inactivating ⁇ -glucosidase mutations.
  • cellulosic biomass or a saccharide may induce the mutant cell to secrete 1.2, 1.4, 1.6, 1.8, 2, 4, 6, 8, 10, 50, 100, 500, 1,000, 5,000, or 10,000-fold higher levels of at least one type of protein after a two day induction compared to that of a cell lacking the inactivating ⁇ -glucosidase mutations.
  • cellulosic biomass or a saccharide may induce the mutant cell to secrete 1.2, 1.4, 1.6, 1.8, 2, 3, 4, 5, 6, 7, 8, 9, or 10-fold higher levels of total protein after a two day induction compared to that of a cell lacking the inactivating ⁇ -glucosidase mutations.
  • the mutant cells may transcribe 10, 50, 100, 500, 1,000, 5,000, 10,000, 50,000 or 100,000-fold higher levels of at least one type of protein after induction with at least 1 nM, at least 5 nM, at least 10 nM, 15 nM, at least 20 nM, at least 25 nM, 30 nM, at least 35 nM, at least 40 nM, 45 nM, at least 50 nM, at least 55 nM, 60 nM, at least 65 nM, at least 70 nM, at least 75 nM, 80 nM, at least 85 nM, 90 nM, at least 95 nM, at least 100 nM, at least 125 nM, 150 nM, at least 175 nM, 200 nM, at least 225 nM, at least 250 nM, at least 275 nM, 300 nM, at least 325 nM, 350 nM, at least 375
  • the mutant cells may secrete 2, 4, 8, 16, 32, 64, 128, or 256 fold higher levels of at least one type of protein after induction with at least 1 nM, at least 5 nM, at least 10 nM, 15 nM, at least 20 nM, at least 25 nM, 30 nM, at least 35 nM, at least 40 nM, 45 nM, at least 50 nM, at least 55 nM, 60 nM, at least 65 nM, at least 70 nM, at least 75 nM, 80 nM, at least 85 nM, 90 nM, at least 95 nM, at least 100 nM, at least 125 nM, 150 nM, at least 175 nM, 200 nM, at least 225 nM, at least 250 nM, at least 275 nM, 300 nM, at least 325 nM, 350 nM, at least 375 nM, at least 400
  • the at least two ⁇ -glucosidase genes are at least three ⁇ -glucosidase genes, at least four ⁇ -glucosidase genes, at least five ⁇ -glucosidase genes, at least six ⁇ -glucosidase genes, at least seven ⁇ -glucosidase genes or more ⁇ -glucosidase genes.
  • the ⁇ -glucosidase genes NCU00130, NCU04952, and NCU08755 are deleted in a N. crassa cell.
  • the mutant cell including inactivating mutations that reduce the activities of at least two ⁇ -glucosidases further includes an inactivating mutation in the cre-1 gene, where cellulosic biomass or a saccharide induces the cell to secrete higher levels of at least one protein than a cell lacking a mutation in the cre-1 gene.
  • Inactivating mutations may affect the expression levels of mutated genes or affect the functional activity of proteins or RNAs encoded by mutated genes. Inactivating mutations may be cis- or trans-acting.
  • Inactivating mutations may be introduced by random mutagenesis, including irradiation or exposure to mutagenic chemicals, or they may be introduced in a targeted manner, including homologous recombination and crossing of strains that include single or multiple inactivating mutations.
  • cellulosic biomass or a saccharide may induce the mutant cell to transcribe 2, 4, 6, 8, 10, 50, 100, 500, 1,000, 5,000, 10,000, 50,000, or 100,000-fold higher levels of at least one type of protein compared to that of a cell lacking the inactivating creA/cre-1 mutation.
  • cellulosic biomass or a saccharide may induce the mutant cell to secrete 1.2, 1.4, 1.6, 1.8, 2, 4, 6, 8, 10, 50, 100, 500, 1,000, 5,000, or 10,000-fold higher levels of at least one type of protein compared to that of a cell lacking the ⁇ -glucosidase mutations or the cre-1 mutation.
  • cellulosic biomass or a saccharide may induce the mutant cell to secrete 1.2, 1.4, 1.6, 1.8, 2, 3, 4, 5, 6, 7, 8, 9, or 10-fold higher levels of total protein after a two-day induction than a cell lacking the ⁇ -glucosidase mutations or the cre-1 mutation.
  • the mutant cell may transcribe 10, 50, 100, 500, 1,000, 5,000, 10,000, 50,000 or 100,000-fold higher levels of at least one type of protein after induction with 1 nM, at least 5 nM, at least 10 nM, 15 nM, at least 20 nM, at least 25 nM, 30 nM, at least 35 nM, at least 40 nM, 45 nM, at least 50 nM, at least 55 nM, 60 nM, at least 65 nM, at least 70 nM, at least 75 nM, 80 nM, at least 85 nM, 90 nM, at least 95 nM, at least 100 nM, at least 125 nM, 150 nM, at least 175 nM, 200 nM, at least 225 nM, at least 250 nM, at least 275 nM, 300 nM, at least 325 nM, 350 nM, at least 375 n
  • the mutant cell may secrete 1.2, 1.4, 1.6, 1.8, 2, 4, 8, 16, 32, 64, 128, or 256 fold higher levels of at least one type of protein after induction with 1 nM, at least 5 nM, at least 10 nM, 15 nM, at least 20 nM, at least 25 nM, 30 nM, at least 35 nM, at least 40 nM, 45 nM, at least 50 nM, at least 55 nM, 60 nM, at least 65 nM, at least 70 nM, at least 75 nM, 80 nM, at least 85 nM, 90 nM, at least 95 nM, at least 100 nM, at least 125 nM, 150 nM, at least 175 nM, 200 nM, at least 225 nM, at least 250 nM, at least 275 nM, 300 nM, at least 325 nM, 350 nM, at least 5 nM, at least
  • the at least two ⁇ -glucosidases are at least three ⁇ -glucosidases.
  • ⁇ -glucosidase genes NCU00130, NCU04952, and NCU08755 and the cre-1 gene are deleted in a N. crassa cell.
  • a mutant cell of the present disclosure contains an inactivating mutation in the creA/cre-1 gene, which causes a loss of the CreA/CRE-1 function encoded by the gene.
  • Inactivating mutations of the creA/cre-1 gene include, without limitation, deletion mutations, point mutations, nonsense mutations, truncations, and insertions. Inactivating mutations may completely abolish CreA/CRE-1 activity or inhibit CreA/CRE-1 activity by at least 75%, at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or more.
  • Inactivating mutations may affect the expression levels of mutated genes or affect the functional activity of proteins or RNAs encoded by mutated genes. Inactivating mutations may also be cis- or trans-acting. Inactivating mutations may be introduced by random mutagenesis, including irradiation or exposure to mutagenic chemicals, or they may be introduced in a targeted manner, including homologous recombination and crossing of strains that include inactivating mutations. As used herein, “cre-1 gene” and “creA/cre-1 gene” are used interchangeably.
  • cellulosic biomass or a saccharide may induce the mutant cell to transcribe 2, 4, 6, 8, 10, 50, 100, 500, 1,000, 5,000, 10,000, 50,000, or 100,000-fold higher levels of at least one type of protein compared to that of a cell lacking the inactivating cre-1 mutation.
  • cellulosic biomass or a saccharide may induce the mutant cell including the inactivating mutation of cre-1 to secrete 1.2, 1.4, 1.6, 1.8, 2, 4, 6, 8, 10, 50, 100, 500, 1,000, 5,000, or 10,000-fold higher levels of at least one type of protein compared to that of a cell lacking the inactivating cre-1 mutation.
  • the mutant cells exhibit elevated basal levels of expression of genes involved in C-compound/carbohydrate metabolism, extracellular metabolism, proteins with binding function or cofactor requirement, C-compound/carbohydrate transport, transport facilities, and protein synthesis relative to a cell lacking the cre-1 mutation.
  • the cre-1 gene is deleted in a N. crassa cell.
  • the mutant cell including an inactivating mutation in the cre-1 gene further includes inactivating mutations, which abolish the ⁇ -activity encoded by the at least two ⁇ -glucosidase genes.
  • Inactivating mutations of the at least two ⁇ -glucosidase genes include deletions, point mutations, nonsense mutations, truncations, and insertions. Inactivating mutations may completely abolish ⁇ -glucosidase activity or inhibit the activity by at least 75%, at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or more.
  • Inactivating mutations may affect the expression levels of mutated genes or affect the functional activity of proteins or RNAs encoded by mutated genes. Inactivating mutations may be cis- or trans-acting. Inactivating mutations may be introduced by random mutagenesis, including irradiation or exposure to mutagenic chemicals, or they may be introduced in a targeted manner, including homologous recombination and crossing of strains that include inactivating mutations.
  • the ⁇ -glucosidases may be intracellular or extracellular (i.e., secreted) ⁇ -glucosidases.
  • cellulosic biomass or a saccharide may induce the mutant cell to transcribe 2, 4, 6, 8, 10, 50, 100, 500, 1,000, 5,000, 10,000, 50,000, or 100,000-fold higher levels of at least one type of protein compared to that of a cell lacking the inactivating ⁇ -glucosidase mutations.
  • cellulosic biomass or a saccharide may induce induces the mutant cell to secrete 1.2, 1.4, 1.6, 1.8, 2, 4, 6, 8, 10, 50, 100, 500, 1,000, 5,000, or 10,000-fold higher levels of at least one type of protein compared to that of a cell lacking the inactivating mutations in the at least two ⁇ -glucosidase mutations.
  • the at least two ⁇ -glucosidases are three ⁇ -glucosidases.
  • the mutant cell is a N. crassa cell including deletions of the ⁇ -glucosidases genes NCU00130, NCU04952, and NCU08755 and a deletion of cre-1.
  • mutant cells containing inactivating mutations that reduce the activities of at least two ⁇ -glucosidases of the present disclosure comprising mutant cells containing an inactivating mutation in the cre-1 gene of the present disclosure; and/or mutant cells containing inactivating mutations that reduce the activities of at least two ⁇ -glucosidases and an inactivating mutation in the cre-1 gene further include a mutation that reduces the activity of at least one ⁇ -mannosidase gene.
  • ⁇ -Mannosidase genes of the present disclosure encode ⁇ -mannosidase enzymes.
  • ⁇ -mannosidase “mannan endo-1,4- ⁇ -mannosidase,” “endo-1,4- ⁇ -mannanase,” “endo- ⁇ -1,4-mannase,” “ ⁇ -mannanase B,” “ ⁇ -1,4-mannan 4-mannanohydrolase,” “endo- ⁇ -mannanase,” “ ⁇ -D-mannanase,” and “1,4- ⁇ -D-mannan mannanohydrolase” are used interchangeably and refer to an enzymes capable of the random hydrolysis of 1,4- ⁇ -D-mannosidic linkages in mannans, galactomannans and glucomannans (EC 3.2.1.78).
  • the at least one ⁇ -mannosidase gene is NCU00890, T. reesei protein ID 62166, T. reesei protein ID
  • a mutant cell of the present disclosure contains inactivating mutations in at least one ⁇ -mannosidase gene, which causes a loss of the ⁇ -mannosidase function encoded by the gene.
  • Inactivating mutations of the at least one ⁇ -mannosidase gene include, without limitation, deletion mutations, point mutations, nonsense mutations, truncations, and insertions.
  • Inactivating mutations may completely abolish ⁇ -mannosidase activity or inhibit ⁇ -mannosidase activity by at least 75%, at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or more.
  • Inactivating mutations may affect the expression levels of mutated genes or affect the functional activity of proteins or RNAs encoded by mutated genes. Inactivating mutations may also be cis- or trans-acting. Inactivating mutations may be introduced by random mutagenesis, including irradiation or exposure to mutagenic chemicals, or they may be introduced in a targeted manner, including homologous recombination and crossing of strains that include inactivating mutations.
  • cellulosic biomass or a saccharide may induce the mutant cell further containing the inactivating mutation of at least one ⁇ -mannosidase gene to transcribe 2, 4, 6, 8, 10, 50, 100, 500, 1,000, 5,000, 10,000, 50,000, or 100,000-fold higher levels of at least one type of protein compared to that of a cell lacking the inactivating mutation of the at least one ⁇ -mannosidase gene.
  • cellulosic biomass or a saccharide may induce the mutant cell further containing the inactivating mutation of at least one ⁇ -mannosidase gene to secrete 1.2, 1.4, 1.6, 1.8, 2, 4, 6, 8, 10, 50, 100, 500, 1,000, 5,000, or 10,000-fold higher levels of at least one type of protein compared to that of a cell lacking the inactivating mutation of the at least one ⁇ -mannosidase gene.
  • the at least one ⁇ -mannosidase gene is deleted in a N. crassa cell.
  • mutant cells containing inactivating mutations that reduce the activities of at least two ⁇ -glucosidases of the present disclosure further contain an inactivating mutation that reduces the activity of at least one phospholipase gene or phospholipase-like gene.
  • a “phospholipase-like gene” is a gene having sequence homology to a phospholipase gene, or a gene encoding a protein having amino acid sequence homology to a phospholipase.
  • a phospholipase-like gene of the present disclosure may be NCU06650. While NCU06650 has not been shown to encode a protein having phospholipase activity, the closest related homologues of the encoded amino acid sequence are phospholipases.
  • Phospholipase genes of the present disclosure encode phospholipase enzymes.
  • phospholipase enzymes include, without limitation, any enzyme that hydrolyzes phospholipids into, for example, fatty acids and other lipophilic molecules.
  • Phospholipase-encoding genes may include, without limitation, genes that encode a phospholipase A1, a phospholipase A2, a phospholipase B, a phospholipase C, a phospholipase D, or a phosphodiesterase.
  • the at least one phospholipase gene or phospholipase-like gene is NCU06650, T. reesei protein ID 67579, homologues thereof, and orthologues thereof.
  • a mutant cell of the present disclosure contains inactivating mutations in at least one phospholipase gene or phospholipase-like gene, which causes a loss of the protein function encoded by the gene.
  • Inactivating mutations of the at least one phospholipase gene or phospholipase-like gene include, without limitation, deletion mutations, point mutations, nonsense mutations, truncations, and insertions.
  • Inactivating mutations may completely abolish phospholipase activity or inhibit phospholipase activity by at least 75%, at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or more.
  • Inactivating mutations may affect the expression levels of mutated genes or affect the functional activity of proteins or RNAs encoded by mutated genes. Inactivating mutations may also be cis- or trans-acting. Inactivating mutations may be introduced by random mutagenesis, including irradiation or exposure to mutagenic chemicals, or they may be introduced in a targeted manner, including homologous recombination and crossing of strains that include inactivating mutations.
  • cellulosic biomass or a saccharide may induce the mutant cell further containing the inactivating mutation of at least one phospholipase gene or phospholipase-like gene to transcribe 2, 4, 6, 8, 10, 50, 100, 500, 1,000, 5,000, 10,000, 50,000, or 100,000-fold higher levels of at least one type of protein compared to that of a cell lacking the inactivating mutation of the at least one phospholipase gene or phospholipase-like gene.
  • cellulosic biomass or a saccharide may induce the mutant cell further containing the inactivating mutation of at least one phospholipase gene or phospholipase-like gene to secrete 1.2, 1.4, 1.6, 1.8, 2, 4, 6, 8, 10, 50, 100, 500, 1,000, 5,000, or 10,000-fold higher levels of at least one type of protein compared to that of a cell lacking the inactivating mutation of the at least one phospholipase gene or phospholipase-like gene.
  • the at least one phospholipase gene or phospholipase-like gene is deleted in a N. crassa cell.
  • Another aspect of the present disclosure relates to recombinant cells exhibiting reduced expression of at least two ⁇ -glucosidase genes or a cre-1 gene in the cell, that also exhibit increased secretion at least one, at least two, at least three, at least four, at least five, or more types of proteins in response to cellulosic biomass or a saccharide; and to methods of using such cells to increase secretion of a protein from the cell, and to degrade lignocellulosic biomass.
  • Recombinant cells of the present disclosure may be stable cell lines or transiently transfected cells.
  • Recombinant cells of the present disclosure exhibiting reduced expression of a gene of interest may contain a mutation that reduces expression of the gene of interest.
  • a gene of interest e.g., a ⁇ -glucosidase gene, a cre-1 gene, a ⁇ -mannosidase gene, or a phospholipase gene or phospholipase-like gene
  • recombinant cells of the present disclosure may be transgenic cells that contain a recombinant construct, such as an inhibitory oligonucleotide, that targets and reduces expression of the gene of interest.
  • Non-limiting examples of inhibitory oligonucleotides include siRNA, miRNA, antisense DNA. Additionally, the expression of a gene of interest may be reduced by gene silencing techniques, such quelling and meiotic silencing. Gene silencing techniques can target the gene of interest, RNA of the gene of interest, a regulator protein of the gene of interest.
  • Types of proteins that may be secreted by recombinant cells of the present disclosure include, without limitation, cellulose-induced proteins.
  • cellulose-induced proteins include, without limitation, cellulases, GH61 enzymes, cellobiose dehydrogenases, lactonases, carbohydrate esterases, polysaccharide lyases, and cellulose binding domain-containing proteins.
  • a secreted protein of the present disclosure is encoded by NCU07340, NCU09680, NCU07898, NCU00762, NCU08760, NCU05057, NCU02240, NCU07190, NCU07898, NCU08760, NCU00206, NCU07143, NCU09491, NCU09664, NCU05598, NCU09764, or NCU05137.
  • recombinant cells of the present disclosure have increased secretion of at least one, at least two, at least three, at least four, at least five, or more types of proteins.
  • a recombinant cell of the present disclosure exhibits reduced expression of at least two ⁇ -glucosidase genes compared to the expression of the at least two ⁇ -glucosidase genes in a corresponding non-recombinant cell. In other embodiments, a recombinant cell of the present disclosure exhibits reduced expression of a cre-1 gene compared to the expression of the cre-1 gene in a corresponding non-recombinant cell.
  • a “corresponding non-recombinant cell” refers to a cell that is of the same species as the recombinant cell and has been cultured under the same conditions as the recombinant cell, but lacks the modification of the recombinant cell that results in reduced gene expression in the recombinant cell.
  • “Reduced expression” of a gene of the present disclosure refers to decreased levels of expression of a gene in a modified cell as compared to the levels of expression of the gene in a corresponding non-modified cell.
  • the expression of the at least two ⁇ -glucosidase genes may be reduced by at least 10%, at least 20%, at least 30%, at least 40%, at least 50%, at least 60%, at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%.
  • the expression of the cre-1 gene may be reduced by at least 10%, at least 20%, at least 30%, at least 40%, at least 50%, at least 60%, at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%.
  • the recombinant cell exhibiting reduced expression of at least two ⁇ -glucosidase genes further exhibits reduced expression of the gene creA/cre-1.
  • Means for the reduction of creA/cre-1 expression may be gene silencing techniques, including siRNA, miRNA, antisense DNA, quelling or meiotic silencing.
  • Gene silencing techniques may target creA/cre-1 or a creA/cre-1 regulator protein or RNA.
  • CreA/cre-1 expression may be reduced by at least 10%, at least 20%, at least 30%, at least 40%, at least 50%, at least 60%, at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%.
  • the recombinant cell exhibiting reduced expression of at least two ⁇ -glucosidase genes may also be a cell in which the functional activity of the CreA/CRE-1 transcription factor has been reduced by overexpression of a dominant negative mutant or protein inhibitor.
  • CreA/CRE-1 function may be reduced by at least 10%, at least 20%, at least 30%, at least 40%, at least 50%, at least 60%, at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%.
  • the recombinant cell exhibiting reduced expression of at least two ⁇ -glucosidase genes, and/or the recombinant cell exhibiting reduced expression levels of at least two ⁇ -glucosidase genes and reduced expression levels of the gene creA/cre-1 may further exhibit reduced expression of at least one ⁇ -mannosidase gene of the present disclosure.
  • Means for the reduction of the ⁇ -mannosidase expression include, without limitation, gene silencing techniques, including siRNA, miRNA, antisense DNA, quelling or meiotic silencing. Gene silencing techniques may target the at least one ⁇ -mannosidase gene or a ⁇ -mannosidase gene regulator protein or RNA.
  • ⁇ -Mannosidase gene expression may be reduced by at least 10%, at least 20%, at least 30%, at least 40%, at least 50%, at least 60%, at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%.
  • expression of the ⁇ -mannosidase gene NCU00890 is reduced in a recombinant N. crassa cell.
  • the recombinant cell exhibiting reduced expression of at least two ⁇ -glucosidase genes; the recombinant cell exhibiting reduced expression of at least two ⁇ -glucosidase genes and reduced expression of the gene creA/cre-1; and/or the recombinant cell exhibiting reduced expression of at least two ⁇ -glucosidase genes, reduced expression of the gene creA/cre-1, and reduced expression of at least one ⁇ -mannosidase gene may further exhibit reduced expression of at least one phospholipase gene or phospholipase-like gene of the present disclosure.
  • Means for the reduction of the phospholipase expression include, without limitation, gene silencing techniques, including siRNA, miRNA, antisense DNA, quelling or meiotic silencing.
  • Gene silencing techniques may target the at least one phospholipase gene or phospholipase-like gene or a gene regulator protein or RNA.
  • Phospholipase gene or phospholipase-like gene expression may be reduced by at least 10%, at least 20%, at least 30%, at least 40%, at least 50%, at least 60%, at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%.
  • expression of the gene NCU06650 is reduced in a recombinant N. crassa cell.
  • expression of the ⁇ -glucosidase genes NCU00130, NCU04952, and NCU08755 is reduced in a recombinant N. crassa cell.
  • expression of the ⁇ -glucosidases genes NCU00130, NCU04952, and NCU08755, and expression of the cre-1 gene is reduced in a recombinant N. crassa cell.
  • expression of the ⁇ -glucosidases genes NCU00130, NCU04952, and NCU08755, expression of the cre-1 gene, and expression of the ⁇ -mannosidase gene NCU00890 is reduced in a recombinant N. crassa cell.
  • expression of the ⁇ -glucosidases genes NCU00130, NCU04952, and NCU08755, expression of the cre-1 gene, expression of the ⁇ -mannosidase gene NCU00890, and expression of the gene NCU06650 is reduced in a recombinant N. crassa cell.
  • the recombinant cell exhibits reduced expression of the cre-1 gene.
  • Means for the reduction of cre-1 expression include, without limitation, gene silencing techniques, including siRNA, miRNA, antisense DNA, quelling or meiotic silencing.
  • Gene silencing techniques may target cre-1 or a cre-1 regulator protein or RNA.
  • Cre-1 expression may be reduced in recombinant cells by at least 10%, at least 20%, at least 30%, at least 40%, at least 50%, at least 60%, at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%.
  • the functional activity of the CreA/CRE-1 transcription factor has been reduced in a recombinant cell by overexpression of a dominant negative mutant or a protein inhibitor.
  • CreA/cre-1 function may be reduced by at least 10%, at least 20%, at least 30%, at least 40%, at least 50%, at least 60%, at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%.
  • Computer implementations of these mathematical algorithms can be utilized for comparison of sequences to determine sequence identity. Such implementations include, but are not limited to: CLUSTAL in the PC/Gene program (available from Intelligenetics, Mountain View, Calif.); the ALIGN program (Version 2.0) and GAP, BESTFIT, BLAST, FASTA, and TFASTA in the Wisconsin Genetics Software Package, Version 8 (available from Genetics Computer Group (GCG), 575 Science Drive, Madison, Wis., USA). Alignments using these programs can be performed using the default parameters.
  • the CLUSTAL program is well described by Higgins et al. (1988) Gene 73:237 244 (1988); Higgins et al. (1989) CABIOS 5:151 153; Corpet et al.
  • Gapped BLAST in BLAST 2.0
  • PSI-BLAST in BLAST 2.0
  • PSI-BLAST in BLAST 2.0
  • sequence identity or identity in the context of two nucleic acid or polypeptide sequences makes reference to the residues in the two sequences that are the same when aligned for maximum correspondence over a specified comparison window.
  • percentage of sequence identity is used in reference to proteins, it is recognized that residue positions which are not identical and often differ by conservative amino acid substitutions, where amino acid residues are substituted for other amino acid residues with similar chemical properties (e.g., charge or hydrophobicity), do not change the functional properties of the molecule.
  • sequences differ in conservative substitutions the percent sequence identity may be adjusted upwards to correct for the conservative nature of the substitution. Sequences that differ by such conservative substitutions are said to have sequence similarity or similarity.
  • Means for making this adjustment are well-known to those of skill in the art. Typically this involves scoring a conservative substitution as a partial rather than a full mismatch, thereby increasing the percentage sequence identity. Thus, for example, where an identical amino acid is given a score of 1 and a non-conservative substitution is given a score of zero, a conservative substitution is given a score between zero and 1. The scoring of conservative substitutions is calculated, e.g., as implemented in the program PC/GENE (Intelligenetics, Mountain View, Calif.).
  • the nucleic acids may be synthesized, isolated, or manipulated using standard molecular biology techniques such as those described in Sambrook, J. et al. 2000. Molecular Cloning: A Laboratory Manual (Third Edition). Techniques may include cloning, expression of cDNA libraries, and amplification of mRNA or genomic DNA.
  • the nucleic acids of the present disclosure, or subsequences thereof, may be incorporated into a cloning vehicle including an expression cassette or vector.
  • the cloning vehicle can be a viral vector, a plasmid, a phage, a phagemid, a cosmid, a fosmid, a bacteriophage, or an artificial chromosome.
  • the viral vector can include an adenovirus vector, a retroviral vector, or an adeno-associated viral vector.
  • the cloning vehicle can include a bacterial artificial chromosome (BAC), a plasmid, a bacteriophage P1-derived vector (PAC), a yeast artificial chromosome (YAC), or a mammalian artificial chromosome (MAC).
  • BAC bacterial artificial chromosome
  • PAC bacteriophage P1-derived vector
  • YAC yeast artificial chromosome
  • MAC mammalian artificial chromosome
  • the nucleic acids may be operably linked to a promoter.
  • the promoter can be a viral, bacterial, mammalian or plant promoter.
  • the promoter can be a constitutive promoter, an inducible promoter, a tissue-specific promoter, or an environmentally regulated or a developmentally regulated promoter.
  • aspects of the present disclosure relate to methods for increasing secretion of a protein from a cell by providing any of the cells of the present disclosure capable of secreting at least one, at least two, at least three, at least four, at least five, or more types of proteins in response to cellulosic biomass or a saccharide; and inducing the cell to secrete the at least two, at least three, at least four, at least five, or more types of proteins by contacting the cell with cellulosic biomass or a saccharide.
  • Cellulosic biomass that may be used with the methods of the present disclosure may include, without limitation, one or more of a polysaccharide, an oligosaccharide, cellulose, microcrystalline cellulose, cellodextrin, cellobiose, cellotriose, cellotetraose, cellopentose, and cellohexose.
  • the cellulosic biomass includes cellobiose.
  • Saccharides that may be used with the methods of the present disclosure include, without limitation, a polysaccharide, an oligosaccharide, cellulose, microcrystalline cellulose, cellodextrin, cellobiose, cellotriose, cellotetraose, cellopentose, cellohexose, and sophorose.
  • the saccharide is cellobiose.
  • Types of proteins that may be secreted by recombinant cells of the present disclosure include, without limitation, cellulose-induced proteins.
  • cellulose-induced proteins include, without limitation, cellulases, GH61 enzymes, cellobiose dehydrogenases, lactonases, carbohydrate esterases, polysaccharide lyases, and cellulose binding domain-containing proteins.
  • a secreted protein of the present disclosure is encoded by NCU07340, NCU09680, NCU07898, NCU00762, NCU08760, NCU05057, NCU02240, NCU07190, NCU07898, NCU08760, NCU00206, NCU07143, NCU09491, NCU09664, NCU05598, NCU09764, or NCU05137.
  • certain aspects of the present disclosure provide methods for increasing secretion of a protein from a cell by: providing a mutant cell, where the mutant cell contains inactivating mutations in two or more ⁇ -glucosidase genes, or contains an inactivating mutation in a cre-1 gene in the cell; and contacting the mutant cell with cellulosic biomass or a saccharide, where the cellulosic biomass or saccharide induces the mutant cell to secrete the protein.
  • the cellulosic biomass or saccharide induces the cell to secrete at least two, at least three, at least four, at least five, or more types of proteins.
  • the method for increasing secretion of a protein from a cell includes the step of inducing the secretion of the protein in the presence of ⁇ -glucosidase inhibitors.
  • the ⁇ -glucosidase inhibitor is nojirimycin.
  • aspects of the present disclosure provide methods for increasing secretion of a protein from a cell, by: providing a recombinant cell, where the recombinant cell exhibits reduced expression of two or more ⁇ -glucosidase genes compared to the expression of the at least two ⁇ -glucosidase genes in a corresponding non-recombinant cell, or exhibits reduced expression of a cre-1 gene compared to the expression of the cre-1 gene in a corresponding non-recombinant cell; and contacting the recombinant cell with cellulosic biomass or a saccharide, where the cellulosic biomass or saccharide induces the recombinant cell to secrete the protein.
  • the cellulosic biomass or saccharide induces the cell to secrete at least two, at least three, at least four, at least five, or more types of proteins.
  • Further aspects of the present disclosure relate to methods for the degradation of biomass by providing lignocellulosic biomass; providing any of the mutant or recombinant cells of the present disclosure; inducing the cell to secrete at least one, at least two, at least three, at least four, at least five, or more types of proteins by contacting the cell with cellulosic biomass or a saccharide; and contacting the induced cell with the lignocellulosic biomass, where the secreted at least one, at least two, at least three, at least four, at least five, or more types of proteins degrade the lignocellulosic biomass.
  • Lignocellulosic biomass generally refers to plant biomass containing cellulose and other carbohydrate polymers that are tightly bound to lignin.
  • suitable lignocellulosic biomass include, without limitation, plant material, municipal solid waste, municipal paper waste, wood residues, sawmill and paper mill discards, and agricultural residues.
  • suitable plant material includes, without limitation, Miscanthus, energy grass, elephant grass, switchgrass, cord grass, rye grass, reed canary grass, common reed, wheat straw, barley straw, canola straw, oat straw, corn stover, soybean stover, oat hulls, oat spelt, sorghum, rice hulls, sugarcane bagasse, corn fiber, barley, oats, flax, wheat, linseed, citrus pulp, cottonseed, groundnut, rapeseed, sunflower, peas, lupines, palm kernel, coconut, konjac, locust bean gum, gum guar, soy beans, Distillers Dried Grains with Solubles (DDGS), Blue Stem, corncobs, pine, conifer softwood, eucalyptus, birchwood, willow, aspen, poplar wood, hybrid poplar, energy cane, short-rotation woody crop, crop residue, yard waste, and
  • Cellulosic biomass that may be used with the methods of the present disclosure may include, without limitation, one or more of a polysaccharide, an oligosaccharide, cellulose, microcrystalline cellulose, cellodextrin, cellobiose, cellotriose, cellotetraose, cellopentose, and cellohexose.
  • the cellulosic biomass includes cellobiose.
  • Saccharides that may be used with the methods of the present disclosure include, without limitation, a polysaccharide, an oligosaccharide, cellulose, microcrystalline cellulose, cellodextrin, cellobiose, cellotriose, cellotetraose, cellopentose, cellohexose, and sophorose.
  • the saccharide is cellobiose.
  • Types of proteins that may be secreted by recombinant cells of the present disclosure include, without limitation, cellulose-induced proteins.
  • cellulose-induced proteins include, without limitation, cellulases, GH61 enzymes, cellobiose dehydrogenases, lactonases, carbohydrate esterases, polysaccharide lyases, and cellulose binding domain-containing proteins.
  • a secreted protein of the present disclosure is encoded by NCU07340, NCU09680, NCU07898, NCU00762, NCU08760, NCU05057, NCU02240, NCU07190, NCU07898, NCU08760, NCU00206, NCU07143, NCU09491, NCU09664, NCU05598, NCU09764, or NCU05137.
  • the method for degrading lignocellulosic biomass includes the step of contacting lignocellulosic biomass with mutant cells of the present disclosure as described above in the presence of ⁇ -glucosidase inhibitors.
  • the ⁇ -glucosidase inhibitor is nojirimycin.
  • lignocellulosic biomass may be subjected to pretreatment including ammonia fiber expansion (AFEX), steam explosion, treatment with alkaline aqueous solutions, acidic solutions, organic solvents, ionic liquids (IL), electrolyzed water, phosphoric acid, and combinations thereof.
  • AFEX ammonia fiber expansion
  • IL ionic liquids
  • Pretreatments that remove lignin from the plant material may increase the overall amount of sugar released from the hemicellulose.
  • the following example relates to the characterization of the cellulase transcription and cellulolytic enzyme production induced in the N. crassa triple ⁇ -glucosidase gene deletion strain and the triple ⁇ -glucosidase and cre-1 gene deletion strain.
  • FGSC Fungal Genetics Stock Center
  • WT Neurospora crassa wild-type
  • ⁇ cre-1 cre-1 gene deletion
  • NCU08755 FGSC 18387 and FGSC 18388
  • NCU04952 FGSC 13731 and FGSC 13732
  • the quadruple deletion produced by performing sequential crosses of the single deletions using the method described by the FGSC (http://www.fgsc.net/neurosporaprotocols/How%20to%20make%20a%20cross-2.pdf).
  • the genotype of all deletion strains was confirmed by using a gene-specific primer and a common primer for the hygromycin (hph) cassette.
  • the forward primer for hph was:
  • hph Middle FWD [SEQ ID NO: 4] 5′-CGA CAG ACG TCG CGG TGA GTT CAG-3′ Reverse primers were:
  • NCU00130 [SEQ ID NO: 5] 5′-TAG TGT ACA AAC CCC AAG C-3′
  • NCU004953 [SEQ ID NO: 6] 5′-AAC ACA CAC ACA CAC ACT GG-3′
  • NCU08755 [SEQ ID NO: 7] 5′-ACA GTG GAG GTG AGA AAG G-3′
  • NCU08807 [SEQ ID NO: 8] 5′-GTA CTT ACG CAG TAG CGT GG-3′
  • RNA from frozen samples was isolated using Zirconia/Silica beads (0.2 g, 0.5 mm diameter; Biospec) and a Mini-Beadbeater-96 (Biospec) with 1 mL TRIzol reagent (Invitrogen) according to manufacturer's instructions.
  • Total RNA was further purified by digestion with TURBO DNA-free (Ambion) and an RNeasy kit (Qiagen). RNA integrity was checked by Nanodrop and agarose gel electrophoresis.
  • Quantitative RT-PCR was performed using the EXPRESS One-Step SYBR GreenER Kit (Invitrogen) and the StepOnePlus Real-Time PCR System (Applied Biosystems). Reactions were performed in triplicate with a total reaction volume of 10 ul including 300 nM each forward and reverse primers and 75 ng template RNA. Data Analysis was performed by the StepOne Software (Applied Biosystems) using Relative Quantitation/Comparative CT ( ⁇ CT). Data was normalized to the endogenous control actin with expression on sucrose as the reference sample. Error bars indicate a 95% confidence interval. The RT-PCR primers were used as described in (Tian et al., 2009).
  • Endo-1,4- ⁇ -Glucanase activity was measured using Azo-CM-Cellulose (Megazyme) according to the manufacturers suggested method. Briefly, 100 ⁇ l Azo-CM-Cellulose substrate solution pre-heated to 37° C. was mixed with 96.5 ⁇ l culture supernatant and 3.5 ⁇ l 3M sodium acetate pH5.0 in a deep-well 96-well plate. Following mixing, the plate was incubated for 10 minutes at 37° C. The reaction was stopped by the addition of 0.5 ml Precipitant Solution and centrifuged for 10 minutes at 1000 g.
  • Exoglucanase (Cellobiohydrolase I) activity was measured using a 4-Methylumbelliferyl ⁇ -D-cellobioside (MuLac) assay.
  • This assay mainly measures the activity of CBH-1 and activity is expressed as the change in fluorescence over time resulting in the slope of a best-fit line as an indication of enzyme activity.
  • any excess sugars in the culture supernatant were removed by passing the supernatant over a 5,000 Dalton concentrator (sartorius stedim Vivaspin 500). Retained proteins were washed twice with 50 mM sodium acetate pH 5 and diluted to 2 ⁇ g/ ⁇ l to assure that the assay remained in the linear range.
  • the assay was performed in a total volume of 1000 containing 10 ⁇ g total protein and had a final concentration of 1.0 mM MuLac and 50 mM sodium acetate pH 5.
  • the assay was performed in a Beckman Coulter Paradigm plate reader set at 40° C. with excitation/emission wavelengths of 360/465 nm with readings every 30 seconds for 10 minutes.
  • the slope of the best-fit line represents the MuLac activity for an individual culture supernatant.
  • the MuLac activity is normalized to the initial dilution required to obtain a concentration in order to represent the undiluted activity.
  • the activity of recombinant cellobiohydrolase-1 was used as a standard and data is presented as a percentage of the wild type activity on Avicel® after 4 days.
  • Avicelase activity was determined according to Tian et al. (Tian et al, 2009) as a measure for glucose and cellobiose concentrations in 7-day culture supernatants from WT, ⁇ cre-1 and other deletion strains.
  • one volume of 7-day culture supernatants from WT and ⁇ cre-1 strains were mixed with one volume of substrate solution containing 5 mg/ml Avicel® and 50 mM NaAc buffer, pH 5.0 at 37° C. After 5 hours of shaking glucose and cellobiose concentrations were measured by coupled enzyme assays.
  • NCU08755, NCU04952, and NCU00130 Three ⁇ -glucosidases (NCU08755, NCU04952, and NCU00130) have been shown to be significantly increased at the transcriptional level during growth of WT N. crassa on Avicel® or Miscanthus (Tian et al, 2009). Additionally, NCU04952 was identified as a secreted protein by mass spectrometry (Tian et al, 2009). To determine whether these three ⁇ -glucosidases play a role in the induction of cellulases on cellobiose, three strains containing deletions of single ⁇ -glucosidases were screened by qRT-PCR for cellobiose-mediated induction of cellulases.
  • the triple ⁇ -glucosidase deletion strain showed a similar induction phenotype as the WT strain for the three cellulases examined ( FIG. 3 ).
  • the WT strain only shows a 20-fold induction for cbh-1, and no change for cbh-2 or eg-2 compared to their relative expression on sucrose
  • the triple ⁇ -glucosidase mutant shows a very different picture: cbh-1 has a 6,500-fold increase in relative expression over expression on sucrose; cbh-2 has a 2,100-fold increase in relative expression and eg-2 has a 2,200-fold increase in relative expression ( FIG. 3 ).
  • Cre-1 deletion is known to moderately increase the transcription and secretion of cellulases on Avicel®. Similarly, Cre-1 is known to allow for approximately 7-fold increases in the basal level of transcription for cbh-1 and eg-2 on sucrose compared to WT expression on sucrose ( FIG. 4 ). When induced with cellobiose, ⁇ cre-1 shows a 600-fold increase in transcription of cbh-1 and an 80-fold increase in eg-2 above their expression on sucrose in the same strain ( FIG. 3 ). While this increase in expression is significant relative to expression on sucrose, it is dwarfed by the 11,000-fold increase in cbh-1 and the 8000-fold increase in eg-2 seen when ⁇ cre-1 is induced with Avicel® ( FIG. 3 ).
  • FIG. 5 shows that while the WT strain, ⁇ cre-1, and the triple ⁇ -glucosidase deletion show a slight induction due to starvation (three to thirty-fold increases), the triple ⁇ -glucosidase/cre-1 deletion has a larger increase in transcription of cbh-1 and eg-2 under these conditions.
  • Relative to triple ⁇ -glucosidase/cre-1 deletion growth on sucrose, its response to starvation is a 340 and 200-fold induction of cbh-1 and eg-2 respectively.
  • These effects are minor compared to the 10,000 to 20,000-fold induction of cbh-1 and eg-2 observed on Avicel® or cellobiose.
  • FIG. 6 shows that while induction of cellulases in the wild type strain is significantly reduced relative to the deletion strains, the WT cellulase expression is concentration dependent, with the lower 1 mM cellobiose concentration acting as a better inducer than the higher 10 mM concentration.
  • the triple ⁇ -glucosidase deletion shows a very similar result to the wild type culture when induced with sucrose or Avicel®.
  • sucrose there is very little secreted protein (180 ⁇ l/ml) after 2 days ( FIG. 7 ), and those that are secreted have no activity towards MuLac ( FIG. 8 ).
  • Avicel® When induced with Avicel®, by day 4 we can see a significant concentration of proteins in the supernatant ( FIG. 7 ).
  • This culture supernatant has an Azo-CM-Cellulose and MuLac activity similar to that for the wild type cultures at the same time point (5.5 ⁇ g CBHI equivalent) ( FIGS. 8 and 9 ).
  • ⁇ cre-1 Compared to the WT strain, ⁇ cre-1 generally appears to produce more secreted proteins. This is evident not only in the cellobiose and Avicel® induced cultures, but also at 48 hours on sucrose ( FIGS. 7 and 11 ) where the secreted protein concentration is approximately twice that seen for WT (481 ⁇ g/ml vs. 270 ⁇ g/ml). While the ⁇ cre-1 secretes more protein on sucrose, these proteins do not exhibit any activity towards MuLac ( FIG. 8 ). While the most obvious band at 70 kDa, runs at the same molecular weight as CBH-1/2, the lack of activity implies that this is either an inactive form of CBH-1/2 or a different non-cellulolytic protein.
  • ⁇ cre-1 shows a slight increase in cellulase secretion on cellobiose (653 ⁇ g/ml) ( FIG. 7 ), which results in a modest increase in activity towards MuLac (0.8 ug) ( FIG. 8B ).
  • MuLac activity at 4 days is less than the activity of wild type (2.8 ug CBHI equivalent) ( FIG. 8B ).
  • this effect might be due to starvation as the overall protein-banding pattern is generally lighter at 4 days as compared to 3 days ( FIG. 12 ).
  • the triple ⁇ -glucosidase/ ⁇ cre-1 deletion strain is similar to the cre-1 deletion strain in that it seems to constitutively secrete more enzymes than the wildtype and the pattern visible on a protein gel under sucrose or Avicel® induction look very similar for these two strains ( FIG. 11 ).
  • the major difference between the ⁇ cre-1 and triple ⁇ -glucosidase/ ⁇ cre-1 deletion strains is the affect of cellobiose on the activity of the secreted proteins ( FIG. 8 ). By four days on cellobiose, this mutant is capable of producing more than 11 ⁇ g CBHI equivalent, which is even more than is produced on Avicel® at this same timepoint ( FIG. 8B ).
  • the Azo-CMC activity assay indicates that this strain produces a similar amount of endo-1,4- ⁇ -glucanase activity in either an Avicel® or cellobiose inducing culture ( FIG. 9 ).
  • the following example relates to the identification of orthologues of the N. crassa ⁇ -glucosidase genes NCU00130, NCU04952, and NCU08755.
  • BLASTp searches were conducted using the National Center for Biotechnology Information (NCBI) non-redundant amino acid database using the NCU00130, NCU04952, and NCU08755 amino acid sequences as queries. Sequence hits from the BLASTp searches were aligned in MEGA5 using ClustalW2.
  • NCBI National Center for Biotechnology Information
  • Phylogenetic trees were generated using the Neighbor-Joining method (Saitou N. and Nei M., 1987). The evolutionary distances were computed using the Poisson correction method (Zuckerkandl E. and Pauling L., 1965) and are in the units of the number of amino acid substitutions per site. Evolutionary analyses were conducted in MEGA5 (Tamura K., Dudley J., Nei M., and Kumar S., 2007).
  • the phylogenetic tree of the ⁇ -glucosidase NCU00130 is depicted in FIG. 14 .
  • the phylogenetic tree of the ⁇ -glucosidase NCU04952 is depicted in FIG. 15 .
  • the phylogenetic tree of the ⁇ -glucosidase NCU08755 is depicted in FIG. 16 .
  • the following example relates to the identification and characterization of the proteins secreted at higher levels from the triple ⁇ -glucosidase gene deletion N. crassa strain, and the triple ⁇ -glucosidase and cre-1 N. crassa deletion strain.
  • FGSC Fungal Genetics Stock Center
  • NCU00130 wild type (FGSC 2489)
  • deletion strains for the intracellular ⁇ -glucosidase NCU00130 FGSC 11822 and FGSC 11823
  • extracellular ⁇ -glucosidases NCU08755 (FGSC 18387 and FGSC 18388) and NCU04952 (FGSC 13731 and FGSC 13732).
  • the homokaryon cre-1 deletion strain (NCU08807) is described in (44). Multiple deletion strains were made by performing sequential crosses. The genotype of each multiple deletion strain was confirmed using a gene-specific primer and a common primer for the hygromycin (hph) cassette.
  • the hph forward primer used was SEQ ID NO: 4 from Example 1.
  • the reverser primers used for NCU00130, NCU004953, NCU08755, and NCU08807 were the same as those used for Example 1.
  • the reverse primer for NCU00130 was SEQ ID NO: 5
  • the reverse primer for NCU004953 was SEQ ID NO: 6
  • the reverse primer for NCU08755 was SEQ ID NO: 7
  • the reverse primer for NCU08807 was SEQ ID NO: 8.
  • Conidia from strains were inoculated at an OD595 equal to 0.05 in 50 ml Vogel's salts (45) with 2% w/v sucrose in a 250 ml Erlenmeyer flask and grown under constant light at 200 rpm for 16 hours. Biomass was then spun at 4200 rpm for 10 minutes and washed in Vogel's salts twice to remove any excess sucrose. Biomass was then added to a new flask containing 50 ml Vogel's salts supplemented with 1% w/v sucrose, 0.2% w/v cellobiose (Sigma) or 1% w/v Avicel® PH 101 (Sigma). Cultures were induced for 4 hrs under constant light at 200 rpm.
  • the culture biomass was then harvested by filtration over a Whatman glass microfiber filter (GF/F) on a Buchner funnel and washed with 50 ml Vogel's salts.
  • the biomass was flash frozen in liquid nitrogen and stored at ⁇ 80° C. Three independent biological duplicates (flasks) were evaluated for each time point.
  • RNA from frozen samples was isolated using Zirconia/Silica beads (0.5 mm diameter; Biospec) and a Mini-Beadbeater-96 (Biospec) with 1 mL TRIzol reagent (Invitrogen) according to the manufacturer's instructions. The total RNA was further purified by digestion with TURBO DNA-free (Ambion) and an RNeasy kit (Qiagen). RNA concentration and integrity was checked by Nanodrop and agarose gel electrophoresis.
  • Quantitative RT-PCR was performed using the EXPRESS One-Step SYBR GreenER Kit (Invitrogen) and the StepOnePlus Real-Time PCR System (Applied Biosystems). Reactions were performed in triplicate with a total reaction volume of 10 ⁇ l including 300 nM each forward and reverse primers and 75 ng template RNA. Data Analysis was performed by the StepOne Software (Applied Biosystems) using the Relative Quantitation/Comparative CT ( ⁇ CT) setting. Data was normalized to the endogenous control actin with expression on sucrose as the reference sample.
  • the RT-PCR primers used for actin were SEQ ID NO: 9 and SEQ ID NO: 10 from Example 1; the RT-PCR primers used for cbh-1 (NCU07340) were SEQ ID NO: 11 and SEQ ID NO: 12 from Example 1; the RT-PCR primers used for gh6-2 (NCU09680) were SEQ ID NO: 13 and SEQ ID NO: 14 from Example 1; and the RT-PCR primers used for gh5-1 (NCU00762) were SEQ ID NO: 15 and SEQ ID NO: 16 from Example 1 (46, 47).
  • mRNA sequencing was performed using an Illumina kit (RS-100-0801) with isolated RNA.
  • the final cDNA library was quantified by an Agilent bioanalyzer 2000 and sequenced using an Illumina Genome Analyzer-II using standard Illumina operating procedures.
  • GenBank accession numbers (PID), Joint Genome Institute protein ID (JGI), or Broad Institute Fusarium Comparative Database Genes (FGSG) numbers for B-G's used in phylogenetic analysis are as follows; NCU08755: Myceliophthora thermophila , JGI 80304; Aspergillus niger , PID 254674400; Phanerochaete chrysosporium , PID 19352194; Trichoderma reesei , JGI 121735; Fusarium graminearum , FGSG — 06605; Sclerotinia sclerotiorum , PID 156051478; Botryotinia fuceliana , PID 154301968; Penicillium chrysogenum , PID 255942539; Schizophyllum commune , JGI 256304; Postia placenta , JGI 107557.
  • NCU00130 Myceliophthora thermophila , JGI 115968; Aspergillus niger , PID 213437; Phanerochaete chrysosporium , PID 127920; Trichoderma reesei , JGI 120749; Fusarium graminearum , FGSG — 07274; Sclerotinia sclerotiorum , PID 156037816; Botryotinia fuceliana , PID 156037816; Penicillium chrysogenum , PID 255941826; Schizophyllum commune , JGI 57050; Postia placenta , JGI 45922.
  • NCU04952 Myceliophthora thermophila , JGI 66804; Aspergillus terreus , PID 115401928; Phanerochaete chrysosporium , PID 3320413; Trichoderma reesei , JGI 76672; Sclerotinia sclerotiorum , PID 156050519; Botryotinia fuceliana , PID 154293970; Penicillium chrysogenum , PID 255945487; Schizophyllum commune , PID 302694815.
  • the hierarchical clustering analysis was performed using Cluster 3.0 (52) according to the FPKMs in the WT strain on cellulose, WT on cellobiose, mutant strains on cellobiose and mutant strains on cellulose. Prior to clustering, FPKMs were log transformed, normalized across strains/conditions on a per-gene basis and centered on the mean value across strains/conditions. The Pearson correlation coefficient (uncentered) was used as the similarity metric and average linkage as the clustering method.
  • Cellulase production was carried out in a 3.7 L bioreactor (BioEngineering AG) at an operating volume of 1 L.
  • the bioreactor was equipped with one 48 mm Rushton impeller and four equally spaced baffles to provide adequate mixing. Impeller speed was controlled at 200 rpm for 8 hours to allow spore germination followed by 500 rpm for the remainder of the experiment.
  • the temperature was maintained at 25° C., and medium pH was controlled at 5.5 using 40% phosphoric acid and 1:5 diluted ammonium hydroxide.
  • the dissolved oxygen was maintained at a level greater than 20% of the saturation value of the medium by varying the aeration rate between 0.5 and 3 VVM in response to the dissolved oxygen tension.
  • Minimal growth medium with 1% w/v sucrose as the sole carbon source was inoculated with 10 9 conidia. After 24 hours initial growth, cellulase production was induced with either cellobiose or Avicel® added to a final concentration of 0.2% w/v. Supernatant samples were collected at timepoint 0, 12 hours before induction, at induction, as well as 4, 8, 12, 24 and 36 hours post induction. Samples were spun at 4000 rpm for 5 minutes to pellet biomass and the supernatant was filtered through a 0.2 ⁇ m PES filter before being stored at ⁇ 20° C. until all samples were collected.
  • Total Avicelase activity was conducted in 250 mL media bottles incubated at 50° C. on a orbital shaker at 200 rpm. Each bottle contained 1% cellulose (Avicel®) and 50 mM (pH 5.0) sodium acetate in a working volume of 50 mL. Tetracycline (10 m/mL) was added to prevent microbial contamination. Bioreactor culture broth samples were buffer exchanged using a 10 kDa MWCO centrifugal filter to remove any soluble sugars prior to initiating hydrolysis experiments. After pre-incubating the hydrolysis mixture to 50° C., enzyme was added (1 mL filtered culture broth). Samples were taken every 4 hours for the first 12 hours and then every 12 hours thereafter for a total of 48 hours. Hydrolysis experiments were performed in triplicate.
  • Sucrose, fructose, glucose and cellobiose were measured on a DIONEX ICS-3000 HPLC (Dionex Corp., Sunnyvale, Calif.) using a CarboPac PA20 Analytical Column (3 ⁇ 150 mm) and a CarboPac PA20 guard column (3 ⁇ 30 mm) at 30° C. Following injection of 25 ⁇ l of diluted samples, elution was performed with 100 mM KOH (isocratic) at 0.4 ml/min. Sugars were detected using PAD, Four-Potential Carbohydrate Waveform and Peaks were analyzed using the Chromeleon software package.
  • Acetonitrile (Fisher Optima grade, 99.9%) and formic acid (Pierce, 1 mL ampules, 99+%) purchased from Fisher Scientific (Pittsburgh, Pa.), and water purified to a resistivity of 18.2 M ⁇ cm (at 25° C.) using a Milli-Q Gradient ultrapure water purification system (Millipore, Billerica, Mass.), were used to prepare mobile phase solvents for liquid chromatography-mass spectrometry.
  • Trypsin-digested proteins were analyzed using an orthogonal acceleration quadrupole time-of-flight (Q-tof) mass spectrometer that was connected in-line with an ultraperformance liquid chromatograph (UPLC).
  • Peptides were separated using a nanoAcquity UPLC (Waters, Milford, Mass.) equipped with C 18 trapping (180 ⁇ m ⁇ 20 mm) and analytical (100 ⁇ m ⁇ 100 mm) columns and a 10 ⁇ L sample loop.
  • Solvent A was 99.9% water/0.1% formic acid and solvent B was 99.9% acetonitrile/0.1% formic acid (v/v).
  • Sample solutions contained in 0.3 mL polypropylene snap-top vials sealed with septa caps were loaded into the nanoAcquity autosampler compartment prior to analysis. Following sample injection (10 ⁇ L), trapping was performed for 3 min with 100% A at a flow rate of 15 ⁇ L/min. The injection needle was washed with 500 ⁇ L each of solvents A and B after injection to avoid cross-contamination between samples.
  • the elution program consisted of a linear gradient from 8% to 35% B over 30 min, a linear gradient to 95% B over 0.33 min, isocratic conditions at 95% B for 3.67 min, a linear gradient to 1% B over 0.33 min, and isocratic conditions at 1% B for 11.67 min, at a flow rate of 500 nL/min.
  • the analytical column and sample compartment were maintained at 35° C. and 8° C., respectively.
  • the UPLC column exit was connected to a Universal NanoFlow Sprayer nanoelectrospray ionization (nanoESI) emitter that was mounted in the nanoflow ion source of the mass spectrometer (Q-tof Premier, Waters, Milford, Mass.).
  • the nanoESI emitter tip was positioned approximately 3 mm from the sampling cone aperture.
  • the nanoESI source parameters were as follows: nanoESI voltage 2.4 kV, nebulizing gas (nitrogen) pressure 0.15 mbar, sample cone voltage 35 V, extraction cone and ion guide voltages 4 V, and source block temperature 80° C. No cone gas was used.
  • the collision cell contained argon gas at a pressure of 8 ⁇ 10 ⁇ 3 mbar.
  • MS/MS tandem mass spectrometry
  • Ions were fragmented to achieve a minimum total ion current (TIC) of 30,000 cps in the cumulative MS/MS spectrum for a maximum of 2 s.
  • TIC total ion current
  • real-time dynamic exclusion was used to preclude re-selection of previously analyzed precursor ions over an exclusion width of ⁇ 0.2 m/z unit for a period of 300 s.
  • crassa has at least 7 genes encoding predicted ⁇ -glucosidase enzymes, only three (NCU00130, NCU04952 and NCU08755) show a significant increase in transcription during growth on Avicel® or Miscanthus (20). All three of these ⁇ -glucosidases showed significant homology to both predicted and experimentally verified ⁇ -glucosidase enzymes in other filamentous fungi. Based on expression data, we believed that GH1-1 (NCU00130), GH3-3 (NCU08755), and GH3-4 (NCU04952) would be the most relevant enzymes in converting cellobiose to glucose when N. crassa is grown on either Avicel® or cellodextrins as sole carbon sources.
  • the individual ⁇ -glucosidase deletion strains did not show a significant induction of cbh-1, gh6-2, or gh5-1 expression; whereas a ⁇ gh1-1 ⁇ gh3-3 double mutant showed some cellulase gene induction.
  • a strain carrying deletions for all three ⁇ -glucosidase genes ( ⁇ gh1-1, ⁇ gh3-3 and ⁇ gh3-4; ⁇ 3 ⁇ G) showed similar relative expression levels of cbh-1, gh5-1 and gh6-2 when shifted to 0.2% cellobiose as did a WT culture shifted to Avicel® ( FIG. 18A ).
  • the ⁇ 3 ⁇ G strain showed similar relative expression levels of cbh-1, gh5-1 and gh6-2 when shifted to cellobiose, cellotriose, or cellotetraose ( FIG. 17B ).
  • the transcriptional response in the ⁇ 3 ⁇ G mutant was specific for cellobiose and was not due to starvation as the expression of cbh-1 and gh5-1 in WT and the ⁇ 3 ⁇ G strain when transferred to media lacking any carbon source showed only a small increase in transcription levels (less than 50-fold induction). These values are negligible when compared to the 20,000-fold (minimum) induction of cbh-1 and gh5-1 by Avicel® in WT N. crassa and in the ⁇ 3 ⁇ G strain shifted to cellobiose.
  • Carbon catabolite repression acts in filamentous fungi to repress cellulase and hemicellulase gene expression in the presence of preferred carbon sources, such as glucose or sucrose, even when lignocellulose is present (4).
  • the C2H2 zinc finger transcription factor CreA/CRE1/CRE-1 (26) plays a key role in CCR as strains lacking CreA/CRE1/CRE-1 in Aspergillus sp., T. reesei and N. crassa , respectively, produce increased amounts of both cellulases and hemicellulases when grown on cellulose or hemicellulose (21, 27, 28).
  • Quantitative RT-PCR analysis of RNA isolated from an N is a key component of CCR.
  • crassa cre-1 deletion strain ( ⁇ NCU08807) showed that the basal expression of cbh-1 and gh5-1 increased about ten-fold relative to a WT strain.
  • the ⁇ cre-1 strain showed increased induction of cbh-1, gh5-1 and gh6-2 (3,000, 500, and 85-fold, respectively).
  • the level of induction in the ⁇ cre-1 mutant was significantly lower than induction levels obtained for WT exposed to Avicel® or the ⁇ 3 ⁇ G mutant exposed to cellobiose.
  • a ⁇ 3 ⁇ G strain that also carried the ⁇ cre-1 deletion exhibited stronger induction of cbh-1, gh5-1 and gh6-2 than either the WT strain shifted to Avicel® or the ⁇ 3 ⁇ G strain shifted to cellobiose ( FIG. 18A ).
  • RNA-Seq High throughput sequencing
  • NCU06971 the orthologue for xlnR/xyr1 (NCU06971), which plays a major role in the regulation of cellulases in Aspergilli (32) and T. reesei (33), falls into the cellulose regulon.
  • NCU06971 was previously identified as a xlnR/xyr1 homolog in N. crassa (34), its role in plant cell wall degradation is unknown.
  • Hierarchical clustering of genes within the cellulose regulon from expression data of WT transferred to media containing no carbon source, cellobiose or Avicel® and the ⁇ 3 ⁇ G strain transferred to media containing cellobiose or Avicel® resulted in the identification of four distinct expression clusters ( FIG. 20A ).
  • the largest cluster (cluster 2) contained 210 genes that showed high expression in the WT strain on Avicel®, as well as in the ⁇ 3 ⁇ G strain on either cellobiose or under Avicel®-induced conditions.
  • This group of 210 genes contained all 16 predicted cellulases (NCU00762, gh5-1; NCU00836, gh61-7; NCU01050, gh61-4; NCU02240, gh61-1; NCU02344, gh61-12; NCU02916, gh61-3; NCU03328, gh61-6; NCU04854, gh7-2; NCU05057, gh7-1; NCU05121, gh45-1; NCU07190, gh6-3; NCU07340, cbh-1; NCU07760, gh61-2; NCU07898, gh61-13; NCU08760, gh61-5; NCU09680, gh6-2) as well as 3 genes identified to be accessory proteins for cellulose degradation (NCU00206, cdh-1; NCU07143, lac-2; NCU09764, CBM1 containing protein) (20, 35).
  • This cluster also contained 9 hemicellulase genes (NCU02343, gh51-1; NCU02855, gh11-1; NCU04997, gh10-3; NCU05924, gh10-1; NCU05955, gh74-1; NCU07225, gh11-2; NCU07326, gh43-6; NCU08189, gh10-2; NCU09775, gh54-1).
  • 29 are predicted to be active on carbohydrates by CAZy (29) and 76 are predicted to be secreted by signalP, with 25 genes falling into both categories.
  • the remaining 102 genes were grouped into their predicted functional category (31) resulting in 10 genes expected to be involved in C-compound and carbohydrate metabolism; 8 genes involved in protein folding, modification, or transport; and 62 genes encoding unclassified proteins.
  • a small cluster of 36 genes showed high expression levels in either the WT or ⁇ 3 ⁇ G deletion strain when exposed to Avicel® ( FIG. 20A ), but had lower expression levels in the ⁇ 3 ⁇ G deletion strain on cellobiose.
  • This group contained a predicted ⁇ -xylosidase gene (NCU09652, gh43-5) and several other genes encoding proteins active on hemicellulose (NCU00710, acetyl xylan esterase; NCU01900, xylosidase/arabinosidase; NCU00891, xylitol dehydrogenase; and NCU08384, xylose reductase). These results suggest that these genes were induced by the 0.5-1.0% hemicellulose found in Avicel® (20) and are not part of the regulon induced by cellobiose.
  • FIG. 20B When comparing the induction of the ⁇ 3 ⁇ G strain on cellobiose versus WT on Avicel®, a striking pattern appears ( FIG. 20B ).
  • Genes induced in the WT by Avicel® are very close to the value seen in the ⁇ 3 ⁇ G mutant.
  • the FPKM for cbh-1 in the WT on Avicel® is 126,816 ⁇ 53,016, while the FPKM in ⁇ 3 ⁇ G on cellobiose is 130,865.
  • This pattern extends even to the lesser-induced cellulases like NCU07760 (gh61-2), which has a FPKM of 239 ⁇ 62 for WT on Avicel® and 538 for ⁇ 3 ⁇ G mutant on cellobiose.
  • FIGS. 7A-D Industrial filamentous fungi are grown in submerged cultures for high-level production of a variety of products (38).
  • WT After 24 hours growth on sucrose, WT, ⁇ 3 ⁇ G and ⁇ 3 ⁇ G ⁇ cre produce a similar amount of biomass ( ⁇ 3.5 g/L) ( FIGS. 7A-C ).
  • WT did not secrete a significant amount of protein (0.05 mg/mL; FIG. 7C ).
  • the ⁇ 3 ⁇ G and ⁇ 3 ⁇ G ⁇ cre cultures produced 0.12 mg/mL and 0.24 mg/mL protein, respectively, in the supernatant ( FIGS. 7A and 7B ).
  • the cellobiose-induced ⁇ 3 ⁇ G and ⁇ 3 ⁇ G ⁇ cre cultures showed a significant increase in endoglucanase activity over this same period of induction ( FIG. 7F ).
  • the ⁇ 3 ⁇ G ⁇ cre strain had less specific activity than either the WT or ⁇ 3 ⁇ G culture supernatants ( FIG. 21 ).
  • GH glycoside hydrolase
  • N/A gene knockout.
  • Avicel®-induced secretome was identified by AQUA Mass Spectrometry (35). Thirteen proteins represent 91% of the total secretome with all other proteins representing less than 1% of the secretome.
  • the following example relates to the characterization of cellulase activity in N. crassa strains containing deletions of the N. crassa gene NCU00890 and the N. crassa gene NCU06650.
  • N. crassa triple ⁇ -glucosidases gene deletion strain and the N. crassa triple ⁇ -glucosidases gene deletion and cre-1 gene deletion strain were generated as described in Example 1.
  • NCU06650 FGSC 11246 and 11247
  • NCU00890 FGSC 16749
  • FGSC Fungal Genetics Stock Center
  • hph Middle FWD [SEQ ID NO: 4] 5′-CGA CAG ACG TCG CGG TGA GTT CAG-3′
  • Reverse primers were: NCU06650: [SEQ ID NO: 23] 5′-CAT CTC ATA CTC CCT CAT CC-3′
  • NCU00890 [SEQ ID NO: 24] 5′-GGT TGT CTC GGT CGA CAT TG-3′
  • Exoglucanase (Cellobiohydrolase I) activity was measured using a 4-Methylumbelliferyl ⁇ -D-cellobioside (MuLac) assay.
  • This assay mainly measures the activity of CBH-1 and activity is expressed as the change in fluorescence over time resulting in the slope of a best-fit line as an indication of enzyme activity.
  • the assay was performed in a total volume of 1000 containing 20 ⁇ l total culture supernatant and had a final concentration of 1.0 mM MuLac and 50 mM sodium acetate pH 5.
  • the assay was performed in a Beckman Coulter Paradigm plate reader set at 40° C. with excitation/emission wavelengths of 360/465 nm with readings every 30 seconds for 10 minutes.
  • the slope of the best-fit line represents the MuLac activity for an individual culture supernatant.
  • NCU00890 and NCU06650 deletions have both been characterized as hypersecretors, we wanted to examine if combining these deletions with the triple ⁇ -glucosidase and cre-1 deletion strain would increase cellulase secretion.
  • the NCU00890 gene encodes a ⁇ -mannosidase.
  • the NCU06650 gene encodes an characterized polypeptide having closest homology to a phospholipase.
  • T. reesei Homologues of the ⁇ -mannosidase gene NCU00890 were identified in Trichoderma reesei .
  • the T. reesei homologues are found on Scaffold 10, 258215-260779, protein ID 62166; and on Scaffold 4, 877954-880802, protein ID 57857.
  • T. reesei homologues were identified by performing a BLASTp search of either NCU00890 or NCU06650 using the DOE Joint Genome Institute T. reesei database.

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