FIELD OF THE INVENTION
The present invention relates to methods and compositions for treating cellulosic materials, and more specifically, to methods and compositions for desizing, scouring and bleaching cellulosic materials. 
BACKGROUND OF THE INVENTION
The processing of cellulosic material, such as cotton fiber, into a material ready for garment manufacture involves several steps: spinning of the fiber into a yarn; construction of woven or knit fabric from the yarn; and subsequent preparation, dyeing and finishing operations. The preparation process, which may involve desizing (for woven goods), scouring, and bleaching, produces a textile suitable for dyeing or finishing. 
A. Desizing: Woven goods are the prevalent form of textile fabric construction. The weaving process requires a “sizing” of the warp yarn to protect it from abrasion. Starch, polyvinyl alcohol, carboxymethyl cellulose, waxes and acrylic binders are examples of typical sizing agents commonly used in the industry. In order to ensure a high whiteness and/or a good dyeability, the size and other applied must be thoroughly removed. It is generally believed that an efficient desizing is crucial to the subsequent preparation processes, namely, the scouring and bleaching processes. The sized fabric, in either rope or open width form, is contacted with the processing liquid containing the desizing agent. The desizing agent employed depends upon the type of size to be removed. The most common sizing agent for cotton fabric is based upon starch. Therefore, most often, woven cotton fabrics are desized by a combination of hot water, the enzyme alpha amylase and a wetting agent or surfactant. 
B. Scouring: The scouring process removes much of the non-cellulosic compounds naturally found in cotton. In addition to the natural non-cellulosic impurities, scouring can remove residual manufacturing materials introduced, such as spinning, coning or slashing lubricants. Conventional scouring processes typically utilize highly alkaline chemical treatment, which results not only in removal of impurities but also in weakening of the underlying cellulose component of the fiber or fabric. The chemical scouring is followed by extensive rinsing to reduce the risk of re-depositing impurities. Insufficient rinsing yields alkaline residue and uneven removal of impurities on the fabric, which in turn results in uneven dyeing in the subsequent process. Furthermore, chemical scouring creates environmental problems in effluent disposal, due to the chemicals employed and the materials extracted from the fibers. Enzymes have been proposed as an alternative to conventional chemical agents for scouring cellulosic materials. See, e.g., WO 9824965, WO 0071808, JP 6220772, JP 10088472, U.S. Pat. No. 5,912,407; Hartzell et al.,  Textile Res. 68:233 (1998); Hsieh et al., Textile Res. 69:590 (1999); Buchert et al., Text. Chem. Col. & Am. Dyestuff Reptr. 32:48 (2000); and Li et al., Text. Chem. Color. 29:71 (1997).
C. Bleaching: Bleaching of textiles is the final preparation step in the manufacturing of textile fabrics and garments. The purpose of bleaching is to completely remove colored impurities, improve absorbency, and achieve adequate whiteness and dyeability. The most widely used bleaching process in the textile industry is the alkaline hydrogen peroxide process. A conventional textile bleach bath contains: sodium hydroxide, surfactant, optical brightener, stabilizers, and bleaching agents. Bleaching can be carried out in batch wise, semi-continuous, continuous or discontinuous processes. When enzymes are used in either the desizing or scouring process, in order to obtain consistent, high quality results with commercial quantities of textiles, the desizing and/or scouring steps have traditionally been performed separately from the bleaching step because of the high temperature and alkalinity requirement of alkaline peroxide bleaching. 
SUMMARY OF THE INVENTION
The present invention provides methods for single-bath desizing, scouring and bleaching of cellulosic materials, such as, for example, crude fibers, yarn, or woven or knit textiles, made of cotton, linen, flax, ramie, rayon, hemp, jute, or blends of these fibers with each other or with other natural or synthetic fibers. 
The methods of the present invention are carried out by contacting cellulosic materials with (i) an enzyme system and (ii) a bleaching system; by adding the enzyme system and the bleaching system in the same solution containing the cellulosic material to be treated without emptying the bath or rinsing the cellulosic materials between the enzymatic treatment and bleaching steps, i.e., in a single-bath process. The enzyme system and the bleaching system may be added simultaneously to the solution. Alternatively, the enzyme system and the bleaching system may be added sequentially to the solution, in which the cellulosic materials are (i) contacted with the enzyme system for a sufficient time and under appropriate conditions that result in effective bioscouring and/or desizing of the cellulosic material, after which (ii) the bleaching system is added directly to the solution containing cellulosic materials and the enzyme system, that is without emptying the bath or rinsing the cellulosic materials. 
In one aspect of the present invention, methods for treating cellulosic material are disclosed, comprising contacting a cellulosic material with (i) an enzyme system for scouring and/or desizing and (ii) a bleaching system comprising at least one peracid bleaching compound, wherein the enzyme system and the peracid bleaching system are added to the same solution in a single-bath process. 
In one embodiment of this aspect of present invention, the enzyme system and the peracid bleaching system are added sequentially in the single-bath process by first (i) contacting a solution containing the cellulosic material with the enzyme system and incubating the solution contents for a sufficient time and under appropriate conditions to promote effective bioscouring and/or desizing, followed by (ii) adding the peracid bleaching system to the same solution containing the cellulosic material and the enzyme system and incubating to complete the processes. 
In another embodiment of this aspect of present invention, the enzyme system and the peracid bleaching system are added to the solution containing the cellulosic material simultaneously, i.e., at or about the same time or without an intervening incubation step. 
The methods and compositions of present invention provide a product exhibiting a high wettability, high whiteness, and uniformity of mote removal, while having advantages over conventional preparation processes, including: (i) shorter processing times; (ii) conservation of water; and (iii) reduction in waste stream. 
DETAILED DESCRIPTION OF THE INVENTION
According to the present invention, bioscouring and/or desizing are combined with bleaching in a single bath process. 
In one preferred embodiment, the single-bath treatment is carried out by adding the enzyme system and the bleaching system simultaneously to the aqueous solution or wash liquor, comprising (i) adding the enzyme system and a peracid bleaching system simultaneously to an aqueous solution or wash liquor which contains or contacts the cellulosic materials, and (ii) incubating for sufficient time and under appropriate conditions to achieve effective scouring and/or desizing, depending on the enzyme system selected, as well as effective bleaching. 
In another preferred embodiment, the single-bath treatment is carried out by adding the enzyme system and the bleaching system sequentially to the aqueous solution or wash liquor, comprising (i) adding the enzyme system to an aqueous solution or wash liquor which contains or contacts the cellulosic material; (ii) performing a first incubation for sufficient time and under appropriate conditions to initiate and cause effective scouring and/or desizing, depending on the enzyme system selected, and (iii) adding the peracid bleaching system to the same solution containing the cellulosic material and the enzyme system and incubating to complete the processes. 
As used herein, a “cellulosic material” refers to the cellulosic substrate to be treated and includes, for example, cotton, linen, flax, ramie, rayon, hemp, jute, and their blends with other natural or synthetic fibers. The cellulosic materials may also include, for example, crude fiber, yarn, woven or knit textile or fabric, or a garment or finished product. 
As used in the present invention, an “enzyme system” refers to a bioscouring enzyme system and/or a desizing enzyme system. Accordingly, an enzyme system may comprise one or more bioscouring enzymes with or without one or more desizing enzymes or one or more desizing enzymes with or without one or more bioscouring enzymes. 
Any suitable desizing enzyme may be used in the present invention. Preferably, the desizing enzyme is an amylolytic enzyme. More preferably, the desizing enzyme is an alpha or beta amylase and combinations thereof. 
Alpha and beta amylases which are appropriate in the context of the present invention include those of bacterial or fungal origin. Chemically or genetically modified mutants of such amylases are also included in this connection. Preferred alpha-amylases include, for example, alpha-amylases obtainable from Bacillus species, in particular a special strain of  B. licheniformis, described in more detail in GB 1296839. More preferred amylases include Duramyl™, Termamyl™, Fungamyl™ and BAN™ (all available from Novozymes A/S, Bagsvaerd, Denmark), and Rapidase™ and Maxamyl™ (available from Gist-Brocades, Holland). Other preferred amylolytic enzymes are CGTases (cyclodextrin glucanotransferases, EC 22.214.171.124), e.g., those obtained from species of Bacillus, Thermoanaerobactor or Thermoanaero-bacterium.
The desizing enzymes may also preferably be derived from the enzymes listed above in which one or more amino acids have been added, deleted, or substituted, including hybrid polypeptides, so long as the resulting polypeptides exhibit desizing activity. Such variants useful in practicing the present invention can be created using conventional mutagenesis procedures and identified using, e.g., high-throughput screening techniques such as the agar plate screening procedure. 
The desizing enzyme is added to the aqueous solution or wash liquor (i.e., the treating composition) in an amount effective to desize the cellulosic materials. Typically, desizing enzymes, such as alpha-amylases, are incorporated into the treating composition in amount from 0.00001% to 2% of enzyme protein by weight of the composition, preferably in an amount from 0.0001% to 1% of enzyme protein by weight of the composition, more preferably in an amount from 0.001% to 0.5% of enzyme protein by weight of the composition, and even more preferably in an amount from 0.01% to 0.2% of enzyme protein by weight of the composition. The desizing enzyme is preferably used at a level from about 2 to 30,000 KNU/I, more preferably 20-30,000 KNU/I and most preferably 200-300 KNU/I or from about 3-50,000 NAU/I, more preferably 30-5,000 NAU/I, most preferably 350-500 NAU/I. 
Any suitable bioscouring enzyme may be used in the present invention. Preferred bioscouring enzymes include, without limitation, pectinases, proteases, lipases, cutinases and combinations thereof, more preferably, the bioscouring enzyme is a pectinases, and even more preferably, the bioscouring enzyme is a pectate lyase. Pectinases: Any pectinolytic enzyme composition with the ability to degrade the pectin composition of plant cell walls may be used in practicing the present invention. Suitable pectinases include, without limitation, those of fungal or bacterial origin. Chemically or genetically modified pectinases are also encompassed. Preferably, the pectinases used in the invention are recombinantly produced and are mono-component enzymes. 
Pectinases can be classified according to their preferential substrate, highly methyl-esterified pectin or low methyl-esterified pectin and polygalacturonic acid (pectate), and their reaction mechanism, beta-elimination or hydrolysis. Pectinases can be mainly endoacting, cutting the polymer at random sites within the chain to give a mixture of oligomers, or they may be exo-acting, attacking from one end of the polymer and producing monomers or dimers. Several pectinase activities acting on the smooth regions of pectin are included in the classification of enzymes provided by Enzyme Nomenclature (1992), e.g., pectate lyase (EC 126.96.36.199), pectin lyase (EC 188.8.131.52), polygalacturonase (EC 184.108.40.206), exo-polygalacturonase (EC 220.127.116.11), exo-polygalacturonate lyase (EC 18.104.22.168) and exo-poly-alpha-galacturonosidase (EC 22.214.171.124). 
In preferred embodiments of the present invention, the pectinase is a pectate lyase. Pectate lyase enzymatic activity as used herein refers to catalysis of the random cleavage of α-1,4-glycosidic linkages in pectic acid (also called polygalcturonic acid) by transelimination. Pectate lyases are also termed polygalacturonate lyases and poly(1,4-α-D-galacturonide) lyases. 
Any pectate lyase may be used in practicing the present invention. In preferred embodiments, the methods utilize a pectate lyase that exhibits maximal activity at temperatures above about 70° C. Pectate lyases may also preferably exhibit maximal activity at a pH above about 8 and/or exhibit enzymatic activity in the absence of added divalent cations, such as, calcium ions. Non-limiting examples of pectate lyases for use in the present invention include pectate lyases that have been cloned from different bacterial genera such as Erwinia, Pseudomonas, Klebsiella and Xanthomonas, as well as from  Bacillus subtilis (Nasser et al. (1993) FEBS Letts. 335:319-326) and Bacillus sp. YA-14 (Kim et al. (1994) Biosci. Biotech. Biochem. 58:947-949). Purification of pectate lyases with maximum activity in the pH range of 8-10 produced by Bacillus pumilus (Dave and Vaughn (1971) J. Bacteriol. 108:166-174), B. polymyxa (Nagel and Vaughn (1961) Arch. Biochem. Biophys. 93:344-352), B. stearothermophilus (Karbassi and Vaughn (1980) Can. J. Microbiol. 26:377-384), Bacillus sp. (Hasegawa and Nagel (1966) J. Food Sci. 31:838-845) and Bacillus sp. RK9 (Kelly and Fogarty (1978) Can. J. Microbiol. 24:1164-1172) have also been described. Any of the above, as well as divalent cation-independent and/or thermostable pectate lyases, may be used in practicing the invention. In preferred embodiments, the pectate lyase comprises the amino acid sequence of a pectate lyase disclosed in Heffron et al., (1995) Mol. Plant-Microbe Interact. 8: 331-334 and Henrissat et al., (1995) Plant Physiol. 107: 963-976.
The pectinases may be incorporated in the aqueous enzyme solution or wash liquor in an amount from 0.00001% to 2% of enzyme protein by weight of the composition, preferably in an amount from 0.0001% to 1% of enzyme protein by weight of the composition, more preferably in an amount from 0.001% to 0.5% of enzyme protein be weight to the composition, and even more preferably in an amount from 0.01% to 0.2% of enzyme protein by weight of the composition. Pectinases are preferably used at a level from about 2.5 to 500,000 APSU/g fabric, more preferably, at a level from about 25 to 50,000 APSU/g fabric, and most preferably at a level from about 250 to 5,000 APSU/g fabric. 
Proteases: Any protease suitable for use in the present invention may be employed. Suitable proteases include those of animal, vegetable or microbial origin, preferably of microbial origin. Preferably, the protease may be a serine protease or a metalloprotease, more preferably, an alkaline microbial protease or a trypsin-like protease. Examples of proteases include aminopeptidases, including prolyl aminopeptidase (126.96.36.199), X-pro aminopeptidase (188.8.131.52), bacterial leucyl aminopeptidase (184.108.40.206), thermophilic aminopeptidase (220.127.116.11), lysyl aminopeptidase (18.104.22.168), tryptophanyl aminopeptidase (22.214.171.124), and methionyl aminopeptidase (126.96.36.199); serine endopeptidases, including chymotrypsin (188.8.131.52), trypsin (184.108.40.206), cucumisin (220.127.116.11), brachyurin (18.104.22.168), cerevisin (22.214.171.124) and subtilisin (126.96.36.199); cysteine endopeptidases, including papain (188.8.131.52), ficain (184.108.40.206), chymopapain (220.127.116.11), asclepain (18.104.22.168), actinidain (22.214.171.124), caricain (126.96.36.199) and ananain (188.8.131.52); aspartic endopeptidases, including pepsin A (184.108.40.206), Aspergillopepsin I (220.127.116.11), Penicillopepsin (18.104.22.168) and Saccharopepsin (22.214.171.124); and metalloendopeptidases, including Bacillolysin (126.96.36.199). 
Commercially available proteases include Alcalase, Savinase, Primase, Duralase, Esperase, Kannase, and Durazym (available from Novozymes A/S), Maxatase, Maxacal, Maxapem, Properase, Purafect, Purafect OxP, FN2, FN3 and FN4 (available from Genencor International Inc.). 
Also useful in the present invention are protease variants, such as those disclosed in EP 130,756 (Genentech), EP 214,435 (Henkel), WO 87/04461 (Amgen), WO 87/05050 (Genex), EP 251.446 (Genencor), EP 260.105 (Genencor), Thomas et al., (1985), Nature. 318, p. 375-376, Thomas et al., (1987), J. Mol. Biol., 193, pp. 803-813, Russel et al., (1987), Nature, 328, p. 496-500, WO 88/08028 (Genex), WO 88/08033 (Amgen), WO 89/06279 (Novozymes A/S), WO 91/00345 (Novozymes A/S), EP 525 610 (Solvay) and WO 94/02618 (Gist-Brocades N.V.). The activity of proteases can be determined as described in “Methods of Enzymatic Analysis”, third edition, 1984, Verlag Chemie, Weinheim, vol. 5. 
Proteases are preferably incorporated into the aqueous enzyme solution or wash liquor in an amount from 0.00001% to 2% of enzyme protein by weight of the composition, preferably in an amount from 0.0001% to 1% of enzyme protein by weight of the composition, more preferably in an amount from 0.001% to 0.5% of enzyme protein be weight to the composition, and even more preferably in an amount from 0.01% to 0.2% of enzyme protein by weight of the composition. 
Lipases: Any lipase suitable for use in the present invention may be used. Suitable lipases (also termed carboxylic ester hydrolases) preferably include those of bacterial or fungal origin, including triacylglycerol lipases (188.8.131.52) and Phospholipase A 2. (184.108.40.206.). Lipases for use in the present invention include, without limitation, lipases from Humicola (synonym Thermomyces), such as from H. lanuginosa (T lanuginosus) as described in EP 258 068 and EP 305 216 or from H. insolens as described in WO 96/13580; a Pseudomonas lipase, such as from P. alcaligenes or P pseudoalcaligenes (EP 218 272), P cepacia (EP 331 376), P. stutzeri (GB 1,372,034), P. fluorescens, Pseudomonas sp. strain SD 705 (WO 95/06720 and WO 96/27002), P. wisconsinensis (WO 96/12012); a Bacillus lipase, such as from B. subtilis (Dartois et al., Biochem.Biophys. Acta, 1131:253-360, 1993); B. stearothermophilus (JP 64/744992) or B. pumilus (WO 91/16422). Other examples are lipase variants such as those described in WO 92/05249, WO 94/01541, EP 407 225, EP 260 105, WO 95/35381, WO 96/00292, WO 95/30744, WO 94/25578, WO 95/14783, WO 95/22615, WO 97/04079 and WO 97/07202. Preferred commercially available lipase enzymes include Lipolase™ and Lipolase Ultra™, Lipozyme™, Palatase™, Novozym™435, and Lecitase™ (all available from Novovozymes A/S). The activity of the lipase can be determined as described in “Methods of Enzymatic Analysis”, Third Edition, 1984, Verlag Chemie, Weinhein, vol. 4.
Lipases are preferably incorporated in the aqueous enzyme solution or wash liquor in an amount from 0.00001% to 2% of enzyme protein by weight of the composition, preferably in an amount from 0.0001% to 1% of enzyme protein by weight of the composition, more preferably in an amount from 0.001% to 0.5% of enzyme protein be weight to the composition, and even more preferably in an amount from 0.01% to 0.2% of enzyme protein by weight of the composition. 
Cutinases: Any cutinase suitable for use in the present invention may be used, including, for example, the cutinase derived from  Humicola insolens cutinase strain DSM 1800, as described in Example 2 of U.S. Pat. No. 4,810,414.
Cutinases are preferably incorporated in the aqueous enzyme solution in an amount from 0.00001% to 2% of enzyme protein by weight of the composition, preferably in an amount from 0.0001% to 1% of enzyme protein by weight of the composition, more preferably in an amount from 0.001% to 0.5% of enzyme protein be weight to the composition, and even more preferably in an amount from 0.01% to 0.2% of enzyme protein by weight of the composition. 
Suitable bioscouring enzymes also include, for example, bioscouring enzymes derived from the enzymes listed above in which one or more amino acids have been added, deleted, or substituted, including hybrid polypeptides, may be used, so long as the resulting polypeptides exhibit bioscouring activity. Such variants useful in practicing the present invention can be created using conventional mutagenesis procedures and identified using, e.g., high-throughput screening techniques such as the agar plate screening procedure. For example, pectate lyase activity may be measured by applying a test solution to 4 mm holes punched out in agar plates (such as, for example, LB agar), containing 0.7% w/v sodium polygalacturonate (Sigma P 1879). The plates are then incubated for 6 h at a particular temperature (such as, e.g., 75° C.). The plates are then soaked in either (i) 1 M CaCl 2 for 0.5 h or (ii) 1% mixed alkyl trimethylammonium Br (MTAB, Sigma M-7635) for 1 h. Both of these procedures cause the precipitation of polygalacturonate within the agar. Pectate lyase activity can be detected by the appearance of clear zones within a background of precipitated polygalacturonate. Sensitivity of the assay is calibrated using dilutions of a standard preparation of pectate lyase.
Effective scouring typically results in improvement in wettability, when measured using the drop test according to AATCC Test Method 39-1980. Preferably, the wettability of the bleached fabric is 20 seconds or less, most preferably, 10 seconds or less. 
Desizing and bioscouring enzymes for use in the invention may be derived from their cell of origin or may be recombinantly produced, and may be purified or isolated. As used herein, a “purified” or “isolated” enzyme is one that has been treated to remove non-enzyme material or other enzymes derived from the cell in which it was synthesized that could interfere with its enzymatic activity. Typically, the desizing and bioscouring enzyme is separated from the bacterial or fungal microorganism in which it is produced as an endogenous constituent or as a recombinant product. If the enzyme is secreted into the culture medium, purification may comprise separating the culture medium from the biomass by centrifugation, filtration, or precipitation, using conventional methods. Alternatively, the enzyme may be released from the host cell by cell disruption and separation of the biomass. In some cases, further purification may be achieved by conventional protein purification methods, including without limitation ammonium sulfate precipitation; acid or chaotrope extraction; ion-exchange, molecular sieve, and hydrophobic chromatography, including FPLC and HPLC; preparative isoelectric focusing; and preparative polyacrylamide gel electrophoresis. Alternatively, purification may be achieved using affinity chromatography, including immunoaffinity chromatography. For example, hybrid recombinant pectate lyases may be used having an additional amino acid sequence that serves as an affinity “tag”, which facilitates purification using an appropriate solid-phase matrix. 
The desizing and bioscouring enzyme used in the methods of the invention may also be chemically modified to enhance one or more properties that render them even more advantageous, such as, e.g., increasing solubility, decreasing lability or divalent ion dependence, etc. The modifications include, without limitation, phosphorylation, acetylation, sulfation, acylation, or other protein modifications known to those skilled in the art. 
Bleaching Systems: As used in accordance with the present invention, a “peracid bleaching system” comprises one or more peracid bleaching compounds, and optionally, an alkali agent, and optionally, at least one bleach stabilizer. 
Peracid Bleaching Compound: As used in the present invention, a “peracid bleaching compound” or “peroxy acid bleaching compound” is an acid that contains at least one perhydroxyl group ( −OOH). Preferably, the peracid bleaching compound is selected from several classes of organic peroxyacid substances. Preferably, the peracid is a performic acid or carboxylic aliphatic peroxyacids containing a single percarboxylic group and a linear or branched saturated alkyl chain of fewer than 11 carbon atoms. Aliphatic carboxylic peroxyacids containing a linear saturated alkyl chain containing fewer than 6 carbon atoms are also preferred. Examples of such peroxyacids are peracetic acid, perpropanoic acid, per-n-butanoic acid and per-n-pentanoic acid. Peracetic acid is particularly preferred because of its effectiveness and the relative simplicity of methods for its preparation.
In another preferred embodiment of the invention, the organic peroxyacid is selected from diperoxycarboxylic acids containing a linear or branched alkyl chain of fewer than 16 carbon atoms and two percarboxylic groups substituted on carbon atoms situated in alpha-omega positions relative to one another. Examples of such peroxyacids are 1,6-hexanediperoxydioic acid, 1,8-octanediperoxydioic acid, 1,10-decanediperoxydioic acid and 1,12-dodecanediperoxydioic acid. In another preferred embodiment of the invention, the organic peroxyacid is selected from aromatic peroxyacids containing at least one percarboxylic group per benzene nucleus. The aromatic peroxyacids containing only a single percarboxylic group per benzene nucleus will be preferably chosen. An example of such a peroxyacid is peroxybenzoic acid. In yet another preferred embodiment of the invention, an organic peroxyacid is substituted by one or more halogen atoms or by any other organic functional substituents, such as, the carbonyl group (ketone, aldehyde or carboxylic acid), the alcohol group, nitrogen-containing groups such as nitrile, nitro, amine and amide groups, and sulphur-containing groups such as sulpho and mercapto groups. An example of such a peroxyacid is peroxymonosulphuric acid. 
The peracid bleaching compound is added to the aqueous solution or wash liquor (i.e., the treating composition) in an amount effective to remove colored impurities, improve absorbency, and achieve adequate whiteness and/or dyeability. Preferably, the peracid bleaching compound is added to the treating composition in an amount from about 0.01 g/l to about 15 g/l of the composition, more preferably about 0.1 g/l to 10 g/l of the composition, most preferably about 0.5 g/l to 5 g/l of the composition. 
Alkali agents are well known in the art. Preferred alkali agents used in the present invention include, sodium hydroxide, sodium carbonate, sodium bicarbonate, sodium perborate, sodium sulfide and sodium sulfite. The alkali agents are preferably added to the treating composition in an amount from about 0.1 g/l to about 10 g/l of the composition, more preferably, in an amount from about 0.5 to about 5 g/l. 
In another preferred embodiment of the present invention, the bleach composition additionally contains one or more bleach stabilizers The bleach stabilizers preferably comprise agents which are able to adsorb, bind or complex traces of heavy metals. Examples of agents which can be used according to the invention with a bleach-stabilizing action are polyanionic compounds, such as polyphosphates, polycarboxylates, polyhydroxypolycarboxylates, soluble silicates as completely or partially neutralized alkali metal or alkaline earth metal salts, in particular as neutral Na or Mg salts, which are relatively weak bleach stabilizers. Examples of strong bleach stabilizers which can be used according to the invention are complexing agents, such as ethylenediaminetetraacetate (EDTA), diethylenetriaminepentaacetic acid (DTPA), nitrilotriacetic acid (NTA), methyl-glycinediacetic acid (MGDA), .beta.-alaninediacetic acid (ADA), ethylenediamine-N,N′-disuccinate (EDDS) and phosphonates, such as, ethylenediaminetetramethylenephosphonate, diethylenetriaminepentamethylenephosphonate (DTMPA) or hydroxyethylidene-1,1-diphosphonic acid in the form of the acids or as partially or completely neutralized alkali metal salts. 
The bleach stabilizer is preferably added to the treating composition in an amount from about 0.1 to about 5/g liter of the composition, more preferably from about 0.5 to about 2 g/l, and most preferably about 1 g/l. 
The bleach composition according to the invention preferably contains at least one bleach stabilizer, and more preferably, at least one of the above mentioned strong bleach stabilizers. Effective bleaching typically results in one or more of the following properties: (i) a desired whiteness (as determined by Ganz whiteness measurement using, e.g., a Macbeth color eye); (ii) a satisfactory uniformity of mote removal (assessed by visual examination); Preferably, the whiteness of the fabric is 50 Ganz units or higher, and most preferably, 60 Ganz units or higher. 
In some embodiments of the invention, the aqueous solution or wash liquor further comprises other components, including, without limitation, other enzymes, as well as surfactants, antifoaming agents, lubricants, builder systems, and the like, that enhance the scouring and/or bleaching processes and/or provide superior effects related to, e.g., strength, resistance to pilling, water absorbency, and dyeability. 
Other enzymes suitable for use in the present invention include, without limitation, pectinases, proteases, and lipases as described above; and cellulases. Cellulases are classified in a series of enzyme families encompassing endo- and exo- activities as well as cellobiose hydrolyzing capability. The cellulase used in practicing the present invention may be derived from microorganisms which are known to be capable of producing cellulolytic enzymes, such as, e.g., species of Humicola, Thermomyces, Bacillus, Trichoderma, Fusarium, Myceliophthora, Phanerochaete, Irpex, Scytalidium, Schizophyllum, Penicillium, Aspergillus, or Geotricum, particularly  Humicola insolens, Fusarium oxysporum, or Trichoderma reesei. Non-limiting examples of suitable cellulases are disclosed in U.S. Pat. No. 4,435,307; European patent application No. 0 495 257; PCT Patent Application No. WO91/17244; and European Patent Application No. EP-A2-271 004.
The enzymes may be isolated from their cell of origin or may be recombinantly produced, and may be chemically or genetically modified. Typically, the enzymes are incorporated in the aqueous solution at a level of from about 0.0001% to about 1% of enzyme protein by weight of the composition, more preferably from about 0.001% to about 0.5% and most preferably from 0.01% to 0.2%. It will be understood that the amount of enzymatic activity units for each additional enzyme to be used in the methods of the present invention in conjunction with a particular bioscouring enzyme can be easily determined using conventional assays. 
Surfactants suitable for use in practicing the present invention include, without limitation, nonionic (see, e.g., U.S. Pat. No. 4,565,647); anionic; cationic; and zwitterionic surfactants (see, e.g., U.S. Pat. No. 3,929,678); which are typically present at a concentration of between about 0.2% to about 15% by weight, preferably from about 1% to about 10% by weight. Anionic surfactants include, without limitation, linear alkylbenzenesulfonate, α-olefinsulfonate, alkyl sulfate (fatty alcohol sulfate), alcohol ethoxysulfate, secondary alkanesulfonate, alpha-sulfo fatty acid methyl ester, alkyl- or alkenylsuccinic acid, and soap. Non-ionic surfactants include, without limitation, alcohol ethoxylate, nonylphenol ethoxylate, alkylpolyglycoside, alkyldimethylamineoxide, ethoxylated fatty acid monoethanolamide, fatty acid monoethanolamide, polyhydroxy alkyl fatty acid amide, and N-acyl N-alkyl derivatives of glucosamine (“glucamides”). 
Builder systems include, without limitation, aluminosilicates, silicates, polycarboxylates and fatty acids, materials such as ethylenediamine tetraacetate, and metal ion sequestrants such as aminopolyphosphonates, particularly ethylenediamine tetramethylene phosphonic acid and diethylene triamine pentamethylenephosphonic acid, which are included at a concentration of between about 5% to 80% by weight, preferably between about 5% and about 30% by weight. 
Antifoam agents include without limitation silicones (U.S. Pat. No. 3,933,672; DC-544 (Dow Corning), which are typically included at a concentration of between about 0.01% and about 1% by weight. 
The compositions may also contain soil-suspending agents, soil-releasing agents, optical brighteners, abrasives, and/or bactericides, as are conventionally known in the art. 
The manner in which the aqueous solution containing the enzyme and bleaching system is contacted with the cellulosic material will depend upon whether the processing regime is continuous, discontinuous pad-batch or batch. For example, for continuous or discontinuous pad-batch processing, the aqueous enzyme solution is preferably contained in a saturator bath and is applied continuously to the cellulosic material as it travels through the bath, during which process the cellulosic material typically absorbs the processing liquor at an amount of 0.5-1.5 times its weight. In batch operations, the fabric is exposed to the enzyme solution for a period ranging from about 5 minutes to 24 hours at a liquor-to-fabric ratio of 5:1-50:1. 
The aqueous solution or wash liquor typically has a pH of between about 4 and about 11. Preferably, the pH of the treating composition is between about 5 and about 10, preferably between about 7 to about 9, and most preferably about 8 to about 9. The temperature at which the combined scouring and/or desizing and bleaching processes are carried out will depend on the process used. In the case of cold pad batch process, the scouring and/or desizing and bleaching temperature is preferably between about 15° C. and about 45° C., and most preferably between about 25° C. and about 35° C. For continuous and other batch processes, the scouring and/or desizing temperature is preferably between about 35° C. and about 75° C., and most preferably between about 45° C. and about 65° C.; and the bleaching temperature may be between about 30° C. and about 100° C., preferably between about 50° C. and about 100° C., and most preferably between about 60° C. and about 90° C. 
It will be understood that the optimum dosage and concentration of the enzymes, bleaching compounds, bleach stabilizers, and alkali agents, the volume of the aqueous solution or wash liquor, and the pH and temperature will vary, depending on: (i) the nature of the fiber, i.e., crude fiber, yarn, or textile; (ii) whether simultaneous or sequential scouring and bleaching are carried out; (iii) the particular enzyme(s) used, and the specific activity of the enzyme; (iv) the conditions of temperature, pH, time, etc., at which the processing occurs; (v) the presence of other components in the wash liquor; and (vi) the type of processing regime used, i.e., continuous, discontinuous pad-batch, or batch. The optimization of the process conditions can be determined using routine experimentation, such as, by establishing a matrix of conditions and testing different points in the matrix. For example, the amount of enzyme, the temperature at which the contacting occurs, and the total time of processing can be varied, after which the resulting cellulosic materials or textile is evaluated for (a) pectin removal; (b) a scoured property such as, e.g., wettability; and (c) quality of bleaching, such as whiteness. 
In a preferred embodiment, the conditions or treating composition may be adjusted to favor the desizing, scouring or bleaching processes, such as, by adjusting pH, concentration of wetting agent, or concentration of divalent cationic chelator such as ethylene diamine tetraacetate so as to further promote the bleaching process. In a preferred embodiment, the sequential mode may further comprise adjusting one or more properties of the composition of the aqueous solution or wash liquor between steps (ii) and (iii). For example, pH, concentration of wetting agent, or concentration of divalent cationic chelator, such as, ethylene diamine tetraacetate, may be adjusted between steps (ii) and (iii) so as to further promote the bleaching process. The conditions of the first and second incubations may also differ with respect to temperature, agitation, time, and the like. 
The following examples are intended as non-limiting illustrations of the present invention.