Abstract
Profiling of cellulases (endo-type cellulase, exo-type cellulase, and β-glucosidase) of Tremella fuciformis and Hypoxylon truncatum were carried out using crude enzymes from these two microorganisms cultured in sawdust-rice bran medium. Specific activity of the crude enzyme from T. fuciformis toward cellulose powder, Avicel, and p-nitrophenyl-β-D-glucopyranoside was 13.5, 35.9, and 47.6U/mg, respectively. The enzyme did not act on carboxymethyl cellulose (CMC). The crude enzyme from H. truncatum acted toward all substrates tested. Endo-type cellulase from H. truncatum was purified to homogeneity and its enzymatic properties were characterized. Following filtration and centrifugation, the enzyme solution was purified by ammonium sulfate fractionation, heat treatment, ion exchange chromatography, and gel chromatography. Its molecular weight was estimated as 46,000 by SDS-PAGE and 41,000 by gel chromatography, which suggested that the native enzyme is active as a monomer. The enzyme was stable at 60℃ and pH 5.0-6.0. The purified enzyme hydrolyzed cellotetraose, cellopentaose, and cellohexaose, but did not degrade cellobiose or cellotriose. These results suggested that endo-type cellulase from H. truncatum can provide short cellooligosaccharides such as cellobiose, cellotriose, and cellotetraose to compensate for the slight or absent endo-cleavage of the T. fuciformis cellulase system during co-cultivation of these two fungi.
