Cellulases are enzymes which are capable of hydrolysis of the xcex2-D-glucosidic linkages in celluloses. Cellulolytic enzymes have been traditionally divided into three major classes: endoglucanases, exoglucanases or cellobiohydrolases and xcex2-glucosidases (Knowles, J. et al., (1987), TIBTECH 5, 255-261); and are known to be produced by a large number of bacteria, yeasts and fungi.
Although cellulases are used to degrade wood pulp and animal feed, cellulases are primarily used in the treatment of textiles, e.g., in detergent compositions for assisting in the removal of dirt or grayish cast (see e.g., Great Britain Application Nos. 2,075,028, 2,095,275 and 2,094,826) or in the treatment of textiles prior to sale to improve the feel and appearance of the textile. Thus, Great Britain Application No. 1,358,599 illustrates the use of cellulase in detergents to reduce the harshness of cotton containing fabrics.
Cellulases have also been used in the treatment of textiles to recondition used fabrics by making their colors more vibrant (see e.g., The Shizuoka Prefectural Hammamatsu Textile Industrial Research Institute Report, Vol. 24, pp. 54-61 (1986)). Repeated washing of cotton containing fabrics results in a grayish cast to the fabric which is believed to be due to disrupted and disordered fibrils, sometimes called xe2x80x9cpillsxe2x80x9d, caused by mechanical action. This greyish cast is particularly noticeable on colored fabrics. As a consequence, the ability of cellulase to remove the disordered top layer of the fiber and thus improve the overall appearance of the fabric has been of value.
Because of its effectiveness in many industrial processes, there has been a trend in the field to search for specific cellulase compositions or components which have particularly effective performance profiles with respect to one or more specific applications. As possible sources of cellulases, practitioners have focused on fungi and bacteria. For example, cellulase produced by certain fungi such as Trichoderma spp. (especially Trichoderma reesei) have been given much attention because a complete cellulase system capable of degrading crystalline forms of cellulose is readily produced in large quantities via fermentation procedures. This specific cellulase complex has been extensively analyzed to determine the nature of its specific components and the ability of those components to perform in industrial processes (see, Wood et al., xe2x80x9cMethods in Enzymologyxe2x80x9d, 160, 25, pages 234, et seq. (1988). U.S. Pat. No. 5,475,101 (Ward et al.) discloses the purification and molecular cloning of one particularly useful enzyme called endoglucanase III (EGIII) which is derived from Trichoderma reesei. 
PCT Publication No. WO 94/14953 discloses endoglucanases which are encoded by a nucleic acid which comprises any one of a series of DNA sequences, each having 20 nucleotides.
Ooi, et al., Curr. Genet. 18:217-222 (1990) disclose the cDNA sequence coding for endoglucanase F1-CMC produced by Aspergillus aculeatus which contains the amino acid strings NNLWG, ELMIW and GTEPFT. Sakamoto, et al., Curr. Genet. 27:435-439 (1995) discloses the cDNA sequence encoding the endoglucanase CMCase-1 From Aspergillus kawachii IFO 4308 which contains the amino acid strings ELMIW and GTEPFT. Ward, et al., discloses the sequence of EGIII having the amino acid strings NNLWG, ELMIW and GTEPFT. Additionally, two cellulase sequences, one from Erwinia carotovara and Rhodothermus marinus are disclosed in Saarilahti, et al., Gene 90:9-14 (1990) and Hreggvidsson, et al., Appl. Environ. Microb. 62:3047-3049 (1996) which contain the amino acid string ELMIW.
Despite knowledge in the art related to many cellulase compositions having applications in some or all of the above areas, there is a continued need for new cellulase compositions which have improved stability under conditions present in applications for which cellulases are useful, e.g., household and laundry detergents and textile treatment compositions.
According to the present invention, a variant EGIII or EGIII-like cellulase is provided wherein one or more amino acids are modified or deleted to confer improved performance, including stability in the presence of thermal and/or surfactant mediated stress. In another embodiment of the invention, residues critical for the stability of an EGIII-like cellulase are identified.
In a preferred embodiment, a variant EGIII or EGIII-like cellulase is provided, wherein the variant comprises a substitution or deletion at a position corresponding to one or more of residues P201, G170 and/or V210 in EGIII from Trichoderma reesei. 
In a more preferred embodiment of this aspect of the invention, the variant comprises a substitution at a position corresponding to one or more of residues P201C, G170C and/or V210C in EGIII.
In an alternative embodiment, the EGIII-like cellulase of this invention, comprises a substitution at a position corresponding to one or more of residues C190G/S, C221S/P and or C231S/V of H grisea. 
In a different aspect of this embodiment, the EGIII-like cellulase is derived from a fungus, bacteria or Actinomycete. In a preferred aspect, the cellulase is derived from a fungus. In a more preferred aspect, the filamentous fungus. In a most preferred aspect, the filamentous fungus belongs to Euascomycete, in particular Aspergillus spp., Gliocladium spp., Fusarium spp., Acremonium spp., Myceliophtora spp., Verticillium spp., Myrothecium spp., or Penicillium spp.
In another embodiment, the EGIII-like cellulase of this invention is an endoglucanase.
In yet another embodiment of this invention, a DNA that encodes an EGIII-like cellulase is provided. In one aspect of this embodiment, the DNA is on a vector. In another aspect of this embodiment, the DNA is in a host cell transformed with the vector.
In a further embodiment, a method for producing an EGIII-like cellulase of this invention is provided. Specifically, a method is provided comprising the steps of culturing a host cell in a suitable culture medium under suitable conditions to produce cellulase, and obtaining said produced cellulase.
In yet another embodiment, a detergent composition is provided that comprises a surfactant and a variant EGIII-like cellulase comprising a substitution or deletion at a position corresponding to one or more of residues P201, G170 and/or V210 in EGIII from Trichoderma reesei. In a preferred aspect of this embodiment, the variant comprises a substitution at a position corresponding to one or more of residues P201C, G170C and/or V210C in EGIII. In another aspect of this embodiment, the detergent is a laundry detergent. In yet another aspect, the detergent is a dish detergent.
As shown in more detail below, the substitutions identified herein are important to the stability of EGIII and EGIII-like enzymes, particularly under thermal stress. Accordingly it is within the scope of the present invention to use the EGIII or EGIII-like enzyme in textile treatment, e.g., in laundry detergent or stone washing compositions, in the reduction of biomass, in the production of feed additives or treatment of feed, in the treatment of wood pulp for the production of paper or pulp based products, and in the treatment of starch during grain wet milling or dry milling to facilitate the production of glucose, high fructose corn syrup and/or alcohol.