Three cellulases from Melanocarpus albomyces for textile treatment at neutral pH

Culture supernatants from strains of Melanocarpus albomyces, Myceliophthora thermophila, Chaetomium thermophilum, and Sporotrichum thermophilum were tested for their ability to release dye in neutral pH conditions from indigo-dyed cotton-containing fabric in biostoning applications. The supernatants from M. albomyces worked well in biostoning, with low backstaining. Three cellulases were purified to homogeneity from the culture medium of this species. Two of the cellulases were endoglucanases with apparent molecular masses of 20 and 50 kDa. The 20 kDa endoglucanase was a relatively heat-stable cellulase with high pH optimum. The partially purified enzyme crystallized spontaneously at pH 4.0 and 7 °C. The 50 kDa endoglucanase also had activity against 4-methylumbelliferyl-β-d-lactoside (MUL) and was active over a wide range of pH values. The third purified cellulase was the 50 kDa cellobiohydrolase with low MUL activity at acidic pH and detectable activity towards filter paper and acid swollen Solca Floc-cellulose, but no endoglucanase activity. The purified 20 kDa endoglucanase performed well in biostoning of denim fabric at neutral pH. Addition of the purified 50 kDa endoglucanase or the 50 kDa cellobiohydrolase to the 20 kDa endoglucanase decreased backstaining in biostoning.