Production and purification of a novel type of CMCase from Humicola grisea var. thermoidea YH-78.

Abstract

A thermophilic fungus, strain YH-78, identified as Humicola grisea var. thermoidea Cooney et Emerson, was newly isolated from compost heaps. This strain exhibited high CMCase activity in cultures on wheat bran medium (50°C, 4 days), but Avicelase activity in the culture filtrate was very low. The culture filtrate significantly disintegrated filter paper and hydrolyzed carboxymethyl cellulose to 45% as glucose at 50°C. The activity of CMCase in the culture filtrate was partially adsorbed onto Avicel. The CMCase component adsorbed onto Avicel was purified to homogeneity by disc electrophoresis. The purified CMCase component was optimally active at 50°C and pH 5.0, and completely adsorbed onto Avicel at pH 5.0 at 4°C for 10 min. The enzyme showed high activity toward CMC and no activity toward Avicel, but showed a high synergistic action together with the cellulase from Humicola insolens YH-8 on hydrolysis of Avicel.