Induction and characterization of the pl 4.85 mannanase in Sclerotium (Athelia) rolfsii

It was found that the synthesis of mannanase is inducible in Sclerotium rolfsii with bacterial cellulose being the best inducer. Furthermore, mannanase is efficiently produced by this fungus when using the noninductive sugar glucose as the only carbon source. While mannanase is produced in considerable levels under these growth conditions, formation of cellulase activity is negligible. One of the mannanase isoenzymes secreted under these noninductive growth conditions was purified to apparent homogeneity and subsequently characterized. The enzyme has a molecular weight of 98 kDa, an isoelectric point of 4.85, and is both active and stable in the acidic region. Especially its activity at very low pH values is remarkable. It retained more than 50% of its maximum activity at pH 1.6.