Abstract
A mixture of 11 kinds of thermophilic bacilli was cultured on a medium containing municipal sewage sludge and filter paper. Two types of thermophilic cellulases appeared in the culture liquid. Both had an optimum temperature of 60°C. One is a neutral cellulase with an optimum pH of 7.5 and the other is an alkali cellulase with an optimum pH at 10.0. After exposure to pH 12 at 4°C for 24h, the alkali cellulase still retained 90% of its activity. The alkali cellulase activity was stimulated by 1mM Zn2+, but was considerably inhibited by 1mM Cu2+ or 1mM Hg2+. Thus, the alkali cellulase was specified as a new type of thermophilic cellulase having strong alkali tolerance.
