EP0580710A1 - Nouveaux microorganismes et nouvelles enzymes - Google Patents

Nouveaux microorganismes et nouvelles enzymes

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Publication number
EP0580710A1
EP0580710A1 EP92909443A EP92909443A EP0580710A1 EP 0580710 A1 EP0580710 A1 EP 0580710A1 EP 92909443 A EP92909443 A EP 92909443A EP 92909443 A EP92909443 A EP 92909443A EP 0580710 A1 EP0580710 A1 EP 0580710A1
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EP
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Prior art keywords
xylanase
strain
activity
minutes
enzyme
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Application number
EP92909443A
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German (de)
English (en)
Inventor
Indra M. Mathrani
Birgitte K. Ahring
Lisbeth Anker
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Novo Nordisk AS
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Novo Nordisk AS
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Publication of EP0580710A1 publication Critical patent/EP0580710A1/fr
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    • C—CHEMISTRY; METALLURGY
    • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
    • C12Y—ENZYMES
    • C12Y302/00—Hydrolases acting on glycosyl compounds, i.e. glycosylases (3.2)
    • C12Y302/01—Glycosidases, i.e. enzymes hydrolysing O- and S-glycosyl compounds (3.2.1)
    • C12Y302/01032—Xylan endo-1,3-beta-xylosidase (3.2.1.32), i.e. endo-1-3-beta-xylanase
    • C—CHEMISTRY; METALLURGY
    • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
    • C12N—MICROORGANISMS OR ENZYMES; COMPOSITIONS THEREOF; PROPAGATING, PRESERVING, OR MAINTAINING MICROORGANISMS; MUTATION OR GENETIC ENGINEERING; CULTURE MEDIA
    • C12N1/00—Microorganisms, e.g. protozoa; Compositions thereof; Processes of propagating, maintaining or preserving microorganisms or compositions thereof; Processes of preparing or isolating a composition containing a microorganism; Culture media therefor
    • C12N1/20—Bacteria; Culture media therefor
    • C12N1/205—Bacterial isolates
    • C—CHEMISTRY; METALLURGY
    • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
    • C12N—MICROORGANISMS OR ENZYMES; COMPOSITIONS THEREOF; PROPAGATING, PRESERVING, OR MAINTAINING MICROORGANISMS; MUTATION OR GENETIC ENGINEERING; CULTURE MEDIA
    • C12N9/00—Enzymes; Proenzymes; Compositions thereof; Processes for preparing, activating, inhibiting, separating or purifying enzymes
    • C12N9/14—Hydrolases (3)
    • C12N9/24—Hydrolases (3) acting on glycosyl compounds (3.2)
    • C12N9/2402—Hydrolases (3) acting on glycosyl compounds (3.2) hydrolysing O- and S- glycosyl compounds (3.2.1)
    • C12N9/2477—Hemicellulases not provided in a preceding group
    • C12N9/248—Xylanases
    • C—CHEMISTRY; METALLURGY
    • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
    • C12Y—ENZYMES
    • C12Y302/00—Hydrolases acting on glycosyl compounds, i.e. glycosylases (3.2)
    • C12Y302/01—Glycosidases, i.e. enzymes hydrolysing O- and S-glycosyl compounds (3.2.1)
    • C12Y302/01008—Endo-1,4-beta-xylanase (3.2.1.8)
    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
    • D21C5/00—Other processes for obtaining cellulose, e.g. cooking cotton linters ; Processes characterised by the choice of cellulose-containing starting materials
    • D21C5/005—Treatment of cellulose-containing material with microorganisms or enzymes
    • C—CHEMISTRY; METALLURGY
    • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
    • C12R—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES C12C - C12Q, RELATING TO MICROORGANISMS
    • C12R2001/00—Microorganisms ; Processes using microorganisms
    • C12R2001/01—Bacteria or Actinomycetales ; using bacteria or Actinomycetales

Definitions

  • This invention relates to novel microorganisms and to novel enzymes. More specifically, the invention relates to a new spbcies of the genus Dictyoglomus, and to novel enzymes having xylanolytic activity obtainable from the genus Dictyoglomus. The invention also relates to the use of these novel xylanolytic enzymes in pulp and paper industry.
  • thermophilum ⁇ Saiki et al., 1985) is the only valid member of its genus and the only published species which resembles the microorganisms of this invention.
  • D. thermophilum is a thermophilic, strictly anaerobic, chemorganotrophic eubacterium that was isolated from a natural hot spring, whereas the microorganisms of this invention were isolated from a man-made environment well removed from any natural thermophilic site.
  • D. thermophilum uses a wide range of carbohydrates for growth, unlike the organisms of this invention, which use only xylan. During growth, D. thermophilum produces significant quantities of acetate, lactate, and CO 2 , and some H 2 and ethanol as fermentation products.
  • the organisms of this invention make only acetate as a major fermentation product during growth and produce small quantities, 1 mM or less, of H 2 and CO 2 . Additionally, in stationary phase cultures of the microorganisms of this invention produce some butyrate, a compound not previously reported as a fermentation product Dictyoglomus. Both organisms of this invention and D. thermophilum are rod-shaped and form spherical bodies, normally formed by only them and one other group of unrelated organisms. The reported guanine/cytosine content of the cellular deoxyribonucleic acid of D.
  • thermophilum a major genotypic characteristic of bacteria, is 29% (measured by thermal denaturation), significantly different from that of the organisms of this invention which have a guanine/cytosine content of 34% as measured by High Performance Liquid Chromatography.
  • D. thermophilum has thermostable amylases which have been cloned into E. coli. The organisms of this invention do not grow with amylose as substrate and amylase activity has not been detected.
  • the organisms of this invention represent at least a new species of the genus Dictyoglomus.
  • the xylanases we have identified from the organisms of this invention are unlike any enzymes described for any Dictyoglomus reported in the literature. Particularly, they possess especially good characteristics which make them applicable for use in the production of paper pulp and paper.
  • the invention relates to previously undescribed microorganisms belonging to a new species of the genus Dictyoglomus.
  • the invention relates to novel enzymes having xylanase activity and having a broad pH optimum in the range of from 5.0 to 9.0
  • the invention provides a process for the preparation of an enzyme according to the invention, comprising cultivation of a xylanase producing strain of an organism of the invention in a suitable nutrient medium, containing carbon and nitrogen sources and inorganic salts, followed by recovery of the desired enzyme by methods known per se.
  • the invention provides a process for treatment of lignocellulosic pulp, in which the lignocellulosic pulp is treated with an enzyme of the invention.
  • the invention provides an agent for use in the treatment of lignocellulosic pulp, which agent contains an enzyme of the invention.
  • Fig. 1 shows the pH curve for growth of an organism of this invention
  • Fig. 2 shows the temperature curve for growth of an organism of this invention
  • Fig. 3 shows the pH dependent activity (% rel.) of an enzyme preparation of the invention, obtained from a culture supernatant incubated at 68°C ( ⁇ Strain B1 xylanase preparation; A D. thermophilum, DSM 3960, xylanase preparation);
  • Fig. 4 shows the temperature dependent activity (% rel.) of an enzyme preparation of the invention, obtained from cultivation of Strain B1 ( ⁇ Supernatant from culture incubated at 68°C;• Supernatant from culture incubated at 78°C);
  • Fig. 5 shows the temperature dependent activity (% rel.) of an enzyme preparation of the invention, obtained from cultivation of the strain D. thermophilum, DSM 3960, ( ⁇ Supernatant from culture incubated at 68°C; D Supernatant from culture incubated at 78°C);
  • Fig. 6A shows the activity remaining (% rel.) of an enzyme preparation of the invention, obtained from cultivation at 68°C of Strain B1 after heat-treatment at the temperature indicated (o 70°C; ⁇ 80°C; ⁇ 90°C; and ⁇ 98°C);
  • Fig. 6B shows a half-logarithmic plot of half-lives.
  • the arrow indicates the thermal activity number (89°C);
  • Fig. 7 shows the pH curve of the xylanolytic activity (% rel.) of an enzyme preparation of the invention;
  • Fig.8 shows the temperature curve of the xylanolytic activity (% rel.) of an enzyme preparation of the invention
  • Fig. 9 shows the residual activity curve of the xylanolytic activity (% rel.) of an enzyme preparation of the invention
  • Fig. 10 shows the thermal stability of the xylanolytic activity (% rel.) of an enzyme preparation of the invention
  • Fig. 11 shows an absorbance scan curve illustrating the lignin release to the filtrate after treatment with an enzyme preparation of the invention.
  • Fig. 12 shows the monosaccharide composition of the acid hydrolyzed filtrates obtained after treatment with an enzyme preparation of the invention.
  • the invention relates to novel microorganisms belonging to the genus Dictyoglomus.
  • Microorganisms were collected at Kirkniemi, Finland. The sample was pulp-mass and water from a pulp-mass cooling tank of a pulp factory. Microorganisms were isolated from a 70°C, pH 8.3 enrichment culture with beech xylan as substrate.
  • Strain B1 A representative isolate of these novel microorganisms of the invention, designated Strain B1, has been deposited on 28 November 1990 at the DSM,
  • Liquid cultures of the microorganisms in exponential phase cultures contain cells, 5 to 20 ⁇ m in length and 0.3 ⁇ m wide, with rounded ends. Cells occur singly, in pairs, and in bundles lying side by side. Cells in exponential phase do not stain Gram positive and do not bind safranine well, and thus are nearly colourless after Gram Stain preparation. Endospores are not observed and the organism is not motile. Cultures do not spontaneously form spheroplasts, and spheroplasts are not induced by lysozyme. However, cells are sensitive to lysis by lysozyme, as evidential by release of DNA or by microscopic observation.
  • the cell bundles are often swollen, and intermediate forms up to a spherical, "ball of yarn" structures with cells lying on the surface of the sphere are observed.
  • the spherical structures have a diameter of from 5 to 25 ⁇ m and careful examination of the ball structures at high magnification shows that the ball structure has a membrane or wall, and in older cultures cells can be seen peeling away from the ball structures and naked spheres of all sizes are present.
  • the ball structures are empty but in stationary phase cultures a small number of the larger spheres, particularly those from which cells have peeled off, contained small amounts of heterogenous material.
  • the spherical structures are sensitive to lysis by sodium dodecyl sulfate, 3% wt/vol, but the cells are stable, in sodium dodecyl sulfate treated samples, cells are whole, do not appear lysed, though they are not as dark as normal when observed with phase contrast microscopy, are well dispersed, wfth no bundles or spheres visible.
  • Scanning electron micrographs prepared by cryogenic freezing fixation of late exponential phase cultures of the microorganism shows single cells, alone and in bundles, ball structures, and extracellular, slime-like material around the cells in the spherical structures and on the single cells.
  • the cells measure 0.24 ⁇ m in width after cryogenic preparation.
  • the "ball of yarn” nature of the ball structure is easily visible, with cells wrapped around the sphere and lying in parallel, side by side on the surface.
  • Thin sections of late exponential phase cultures examined with transmission electron microscopy show that the microorganism has a thick, extracellular coat not visible with light microscopy and distinct from the cell wall that is visible outside the wall of the cell. No special interior features within the cells are visible. Thin sections through ball structures showed that they are empty and no membranous or wall-like structure lines of the interior of the ball are present after preparation, as observed with phase contrast microscopy.
  • the microorganisms of the invention will only use xylans, beech tree or oat spelt, as carbon and energy sources. There is no growth or metabolism with xylose, xylobiose, arabinose, glucose, fructose, sucrose, galactose, mannose, maltose, rhamnose, lactose, starch, cellobiose, cellulose, peptone, and yeast extract.
  • xylose syrup from Cerestar ® (containing: Xylose, 48-55%; Arabinose, 9-13%; Rhamnose, 3-5%; Mannose, 0.5-1.5%; Galactose, 3-6%; and Glucose, 8-13%) is tested as substrate. All substrates are tested at 4 and 1 g xylan per litre.
  • Major fermentation products from xylan are acetic acid (up to 25 mM), trace levels of hydrogen gas (up to 1 mM), and carbon dioxide. Lactate, formate, or ethanol are not detectable (detection limit 0.25 mM).
  • Microorganisms of this invention are isolated at a relatively high pH and this is reflected in its ability to grow at pH values well over 8.0 and near 9. Optimum growth occurs over a wide range, from pH near 6 to over 8 (Fig. 1), with slow growth at pH 5.0 and no growth at pH 9. The effect of temperature on the growth rate of the microorganisms is shown in Fig. 2. Growth occurs from below 60°C up to over 75°C, but not at 80°C. Best growth occurs from under 65 to over 75°C. Antibiotic Sensitivity
  • the antibiotic sensitivity of the microorganisms of the invention is similar to that of typical eubacteria. It is sensitive to chloramphenicol, kanamycin, penicillin, streptomycin, tetracycline, and vancomycin, all at 100 mg/l. However, the microorganisms are unaffected by ampicillin, chloramphenicol, and tetracycline at 10 mg/l. GC-content Determination
  • the guanosine and cytosine content of the total cellular DNA of the organisms of the invention was determined by HPLC-analysis. In this way the average GC-content measured was 34 mol-%. Table 1
  • the invention in its second aspect, relates to novel enzyme preparations having xylanolytic activity.
  • the xylanase preparations of this invention are produceable by cultivation of a microorganism of the invention, preferably by cultivation of a strain of microorganisms essentially identical to the strain DSM No. 6262, or a mutant or a variant thereof.
  • the xylanase preparations of this invention are also produceable by cultivation of the strain D. thermophilum, DSM 3960, or a mutant or a variant thereof. Most likely these orgamisms are able to produce a complex of xylanases, as indicated by the broad pH range and the pi values determined.
  • the xylanase preparations of this invention can also be obtained by recombinant DNA-technology.
  • the xylanase preparations of the invention can be described by the following characteristics. Physical-chemical Properties
  • the influence of pH on the xylanolytic activity was determined according to Examples 2-3, using the method for xylanase activity analysis described in this specification (20 minutes of incubation; 60°C). The result of the determination is presented in Figs. 3 and 7.
  • the xylanase preparations possess activity at pH values from below 5.0 to above 11.0.
  • the xylanase possesses optimum activity at a pH in the range of from pH 5.0 to 9.0. This broad pH range indicates the presence of more than one xylanase compound.
  • the temperature activity relationship was determined according to Examples 2 and 4, using the method for xylanase activity analysis described in this specification (20 minutes of incubation; pH 6.0). The result of the determination is presented in Figs. 4, 5 and 7.
  • the xylanase possesses activity at temperatures of from below 50°C to above 100°C.
  • the xylanase possesses optimum activity in the range of from 60°C to 90°C, more specifically of from 65°C to 85°C. This broad temperature range also indicates the presence of more than one xylanase compound.
  • the residual activity of the xylanase was determined according to Examples 2 and 5, using the method for xylanase activity analysis described in this specification (20 minutes of incubation; pH 6.0; 60°C).
  • the thermal stability was determined according to Example 2 and 6, using the method for xylanase activity analysis described in this specification (20 minutes of incubation, pH 9.0, 70°C). The result of the determination is presented in Figs.6B and 10.
  • the half life of the xylanase activity for the crude preparation was found to be between 20 and 40 hours, around 30 hours. Between 20-30% of the xylanase activity remain after 60 hours of incubation.
  • the enzyme preparation of the invention has immunochemical properties identical or partially identical (i.e. at least partially identical) to those of a xylanase derived from Strain B1, DSM No. 6262.
  • the immunochemical properties can be determined immunologically by cross-reaction identity tests.
  • the identity tests can be performed by the well-known procedures
  • antigenic identity and “partial antigenic identity” are described in the same book, Chapters 5, 19 and 20.
  • Xylanase is determined by assaying for reducing sugars released from oat spelt xylan (XU-method). The assay is performed with 0.5% oat spelt xylan (Sigma-X-0627), prepared in 40 mM Britton & Robinson buffer (heat treated 30 minutes at 100°C before use), as substrate. The assay is run for 20 minutes at 60°C, using 0.100 ml of enzyme solution and 0.100 ml of substrate, both pre-heated to 60°C. The mixture is incubated for 20 minutes at 60°C.
  • the solution is then heated to 100°C for 20 minutes, and 0.200 ml solution II (50 g (NH 4 ) 6 Mo 7 O 24 ,4H 2 O suspended in 900 ml deionized H 2 O; 42 ml Concentrated H 2 S0 4 ; 6.0 g Na 2 HAsO 4, 7H 2 O ad deionized to a total volume of 1 litre) is added. 2.0 ml deionized water are added, and the absorbance on a spectrophotometer (PYE UniCAM PU8600UV/VIS, Phillips) at 520 nm measured.
  • a spectrophotometer PYE UniCAM PU8600UV/VIS, Phillips
  • the reducing sugars are calculated from a standard curve prepared with xylose (40-400 ⁇ g/ml).
  • One XU is equivalent to 1 nmol xylose released per second per millilitre or per gram of culture broth.
  • the invention relates to a method for enzymatic treatment of lignocellulosic pulp, comprising employment of an enzyme of this invention.
  • Enzymatic treatment of lignocellulosic pulp improves the bleachability of the pulp and/or reduces the amount of chemicals necessary for obtaining a satisfactory bleaching.
  • the enzyme of the invention may also be applied in a complexing stage of the pulp process, prior to hydrogen peroxide or ozone bleaching.
  • the xylanase should preferably be provided in the form of a granulate, preferably a non-dusting granulate, a liquid, in particular a stabilized liquid, a slurry, or a protected enzyme.
  • the agent contains the xylanase in amounts of at least 20%, preferably at least 30%, of the total enzyme protein.
  • the xylanolytic activity can be measured in xylanase units.
  • two kinds of units are used: FXU and EXU.
  • the process of the invention is performed at temperatures between 40 and 100°C, more preferred between 50 and 90°C, most preferred between 60 and 80°C.
  • the enzymatic treatment is performed at a pH above 5.0, more preferred above 6.0, most preferred above 7.0.
  • the enzymatic treatment is performed within a period of 5 minutes to 24 hours, more preferred within 15 minutes to 6 hours, most preferred within 20 minutes to 3 hours.
  • a suitable xylanase dosage will usually correspond to a xylanase activity of 10 to 5000 FXU/kg or EXU/kg dry pulp, more preferred 100 to 5000 FXU/kg or EXU/kg dry pulp.
  • the enzymatic treatment takes place at a consistency of 3-35%, more preferred 5-25%, most preferred 8-15%.
  • the consistency is the dry matter content of the pulp. A pulp with a consistency above 35% is difficult to mix effectively with the enzyme preparation, and a pulp with a consistency below 3% carries too much water, which is a disadvantage from an economic point of view.
  • the xylanases of this invention can be implemented in processes for treatment of lignocellulosic pulp essentially as described in e.g. International Patent Application PCT/DK91/00239, or International Patent Publication WO 91/02839.
  • a Xylanase preparation of strain B1 can be produced as follows. Strain B1 (DSM 6262) is grown in a 1 I glass flask for 2 days at 70°C on the medium as described below.
  • the strain D. thermophilum, DSM 3960 was cultivated in a similar way.
  • ⁇ (h -1 ) specific growth rates, for the identification of the optimum temperature and pH for growth, were determined from the specific acetate production rate.
  • the correlation of acetate production and cell number was determined by counting cells in a Petroff-Hauser counting chamber after treatment with 0.025% sodium dodecyl sulfate to dissolve the spherical structures and separate the cells from each other (vide Svetlichnii and Svetlichnaya, supra).
  • the effects of pH and temperature on the growth rate of Strain B1 are shown in Figs. 1-2.
  • This xylanase preparation which is a total culture, hereafter called P-037, is used as a crude xylanase preparation for further investigation according to Examples 3-8 below.
  • the xylanases of the invention are very thermostable. After 10 hours of incubation at 70°C more than 50% residual activity are detectable, preferably more than 70% residual activity. After 10 hours of incubation at 80°C more than 40% residual activity are detectable, preferably more than 50% residual activity. After 4 hours of incubation at 90°C more than 20% residual activity are detectable.
  • Fig. 6B shows a semi-logarithmic plot of the thermal half-life of the activity of the supernatant xylose preparation of the invention as a function of temperature. At 70°C the thermal half-life was more than 40 hours, approximately 46 hours. At 80°C the thermal half-life was more than 10 hours, approximately 13 hours. At 90°C a substantial amount of activity is still present, approximately 1 hour. The data form a straight line (r 2 > 95%), and the thermal activity number, i.e. the temperature leading to a half-life of 1 hour, was 89°C.
  • pH-characterization of the xylanase activity in Strain B1 is determined using the crude xylanase preparation P-037 described in Example 1 , and the XU-method described earlier in this specification, performed in the pH range of 5 to 11. All assays are performed for 20 minutes at 60°C.
  • the pH optimum of the crude preparation is between pH 5 and 7 (Fig. 7). Between 10-20% of the xylanase activity persist at pH 9. Taking the observations from Example 2 into account, and the fact that activity of the enzyzme misture is presented as % relative activity, pH profile of Fig. 7 may be due to the presence of a substantially larger amount of one or more different xylanolytic enzymes having pH optimum around 6.
  • the temperature profile of the xylanase activity in B1 is determined by using the crude xylanase preparation P-037, described in Example 1 and the XU-method described earlier, performed at pH 6 in the temperature range of 50-100°C. All assays are performed for 20 minutes.
  • the temperature optimum of the crude preparation is found to be between 60 and 80°C (Fig. 8), indicating an optimum around 70°C. Between 30-40% of the xylanase activity remain at 90°C.
  • the thermal stability of the xylanase of B1 is measured as residual activity after heat treatment using the crude xylanase preparation P-037, described in Example 1.
  • Xylanase solutions are heated at 60 to 100°C for half an hour and hereafter the residual xylanase activity is measured using the XU-method described earlier, at pH 6, 60°C for 20 minutes.
  • the result of the determination is presented in Fig. 9. From this Figure it appears that the xylanase possesses a residual activity after 20 minutes at 70°C of more than 50%, more specifically more than 70%, most specifically more than 90%. After 20 minutes at 80°C the xylanase possesses a residual activity of more than 20%, more specifically more than 40%. After 20 minutes at 90°C the xylanase possesses a residual activity of more than 20%.
  • Thermal stability of the xylanase activity in B1 was determined by using the crude xylanase preparation P-037, described in Example 1 and the XU-method described earlier. Solutions of the P-037 were incubated at 70°C, pH 9. Samples were taken with appropriate intervals, and the residual activity was measured using the XU-method described earlier, at pH 9, 70°C for 20 minutes. The result of the determination is presented in Fig. 10. The half-life of the xylanase activity for the crude preparation was found to be between 20 and 40 hours, around 30 hours. Between 20-30% of the xylanase activity remain after 60 hours of incubation.
  • the pl of the xylanase activity was determined using LKB ampholine PAG plates pH 3.5-9.5 and a solution of the crude xylanase preparation P-037, described in Example 1. After the electrophoresis the gel is washed twice for 15 minutes, once in water, once in trisbuffer pH 9, and then overlayered with a thin coat of detection agar consisting of 0.5% of oat spelt xylan, 1% of agarose pH 9. The overlayered gel is incubated overnight at 50°C. The xylanase activity was visualized using Congo Red staining (staining for 10 minutes with 0.1% of Congo Red and destained for 2 X 15 minutes in 1 M NaCI). Congo Red could be detected with pl values between 4 and 7. 4 components with xylanolytic activity could be detected in the range of from 4 to 7.
  • the pl of the xylanase activity was determined also using LKB ampholine PAG plates pH 3.5-9.5 and a solution of the crude xylanase preparation P-037, described in Example 1. Then, in a first set of tests, the solution was subjected to electrophoresis without any intermediate treatment, and in a second set of tests, the solution was heat treated at 70°C at pH 10 (0.1 M bicarbonate buffer) for 60 minutes.
  • the gels were incubated at 70°C overnight and washed for 20 minutes in 0.5 M Trisbuffer, pH 7.0.
  • the xylanase activity was visualized using Congo Red staining (staining for 10 minutes with 0.1% of Congo Red and destained for 2 X 15 minutes in 1 M NaCI).
  • the preparation contains a complex of enzymes with xylanolytic activity.
  • the pl determined above (4 components with xylanolytic activity in the range of from 4 to 7) additional pl values for xylanase activity were determined at 7.4, 8.2, and 8.9, among which the band at 8.9 was the most powerful. Activity blur was observed between 7.4 and 8.9, which is the reason for the figure in the bracket (8.2).
  • the xylanase activity at 8.9 was observed at any of the tests.
  • the bleach boosting effect is demonstrated by a screening method. Being a screening method the experiment, therefore, is not conducted at industrially relevant conditions.
  • a sample of the filtrate after the enzyme treatment step was filtered through a 0.45 ⁇ m filter, freeze dried, hydrolyzed for two hours with 2 N-trifluoroacetic acid (TFA) at 100°C, whereafter the TFA was removed by evaporation and the sample redissolved in demineralized water.
  • TFA N-trifluoroacetic acid
  • the monosaccharide composition of the hydrolyzed sample was then determined by means of an Ion Exchange HPLC system followed by electrochemical detection (for reference see eg. Hardy et al. (1988); Analytical Biochemistry, 17054-62).
  • the Kappa Numbers were analyzed to 13.5 for the control and 12.7 for the enzyme treated pulp. This shows a reduction of 6%, which is a significant improvement at this step in the process.
  • the monosaccharide composition of the acid hydrolyzed filtrates is shown in Fig. 12 below.
  • the xylose comprises 90% of the total monosaccharides whereas glucose is hardly present (-1%).

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Abstract

L'invention concerne de nouveaux microorganismes et de nouvelles enzymes. Plus particulièrement l'invention concerne une nouvelle espèce du genre Dictyoglomus, et de nouvelles enzymes caractérisées par une activité xylanolytique que l'on peut obtenir à partir du genre Distyoglomus. L'invention se rapporte également à l'emploi desdites nouvelles enzymes xylanolytiques dans l'industrie de la pâte à papier et du papier.
EP92909443A 1991-04-18 1992-04-14 Nouveaux microorganismes et nouvelles enzymes Withdrawn EP0580710A1 (fr)

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DK91695A DK69591D0 (da) 1991-04-18 1991-04-18 Nye mikroorganismer
DK695/91 1991-04-18

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EP0580710A1 true EP0580710A1 (fr) 1994-02-02

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EP19920610027 Pending EP0511933A3 (fr) 1991-04-18 1992-04-14 Microorganismes dictyoglomus et leurs enzymes xylanolytiques

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JP2807612B2 (ja) * 1993-03-12 1998-10-08 ノボ ノルディスク アクティーゼルスカブ 新規キシラナーゼ、その製造法、該キシラナーゼによるパルプ処理方法及びキシロオリゴ糖の製造法
US5437992A (en) * 1994-04-28 1995-08-01 Genencor International, Inc. Five thermostable xylanases from microtetraspora flexuosa for use in delignification and/or bleaching of pulp
BR9506262A (pt) * 1994-06-14 1997-08-12 Gist Brocades Bv Xilanase sequência de dna isolada e purificada vetor células hospedeira microbiana microorganismo isolado processos para a preparação de uma xilanase para a degradação de xilano para deslignificar pasta de madeira e produto obtido após o tratamento da pasta de madeira
WO1997027292A1 (fr) * 1996-01-22 1997-07-31 Novo Nordisk A/S Enzyme possedant une activite de type xylanase
WO1997036995A2 (fr) * 1996-03-29 1997-10-09 Pacific Enzymes Limited Xylanase
EP0956348B1 (fr) * 1996-12-20 2006-04-12 Novozymes A/S Endoglucanase
DK2258836T3 (en) 2004-09-10 2016-07-25 Novozymes North America Inc Methods for the prevention, elimination, reduction or destruction of biofilms

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US4966850A (en) * 1987-01-21 1990-10-30 Forintek Canada Corp. Production of thermostable xylanase and cellulase
WO1991002791A1 (fr) * 1989-08-14 1991-03-07 Cultor Oy Blanchiment enzymatique de la cellulose
DK420289D0 (da) * 1989-08-25 1989-08-25 Novo Nordisk As Fremgangsmaade til behandling af lignocellulosepulp

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EP0511933A3 (fr) 1992-11-19
DK69591D0 (da) 1991-04-18
EP0511933A2 (fr) 1992-11-04
JPH06506593A (ja) 1994-07-28
FI934574A (fi) 1993-10-15
NZ242410A (en) 1995-03-28
WO1992018612A1 (fr) 1992-10-29
FI934574A0 (fi) 1993-10-15
CA2108567A1 (fr) 1992-10-19

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