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A mesophilic anaerobe, Acetivibrio cellulolyticus, isolated from a cellulose-enrichment culture, degraded cellulose by the secretion of cellulolytic enzymes into the culture medium. Both exo- and endoglucanase activities were detected and shown to be regulated by induction and catabolite repression. Endoglucanase synthesis was induced by cellulose, cellobiose and salicin. Synthesis induced during growth on cellobiose was inhibited, although not completely repressed by glucose. Exoglucanase activity was enhanced when cells were grown on insoluble or soluble poly beta-glucoside polymers. Activity was progressively inhibited by supplementing microcrystalline substrates with increasing amounts of cellobiose.

The major reasons behind the low efficiency of enzymatic hydrolysis of cellulose are reviewed. The problem is a result of the heterogeneous nature of the hydrolysis reaction which involves a multicomponent soluble catalyst, an insoluble substrate and products which are both.