Cellulolytic activity of the rumen bacterium Bacteroides succinogenes

Abstract

Bacteroides succinogenes S-85 grows readily in media containing 0.2% (w/v) filter paper cellulose or microcrystalline cellulose as the carbohydrate source. During growth, the cells appear to adhere to the cellulose. Cell-free culture supernates and cell extracts from cellulose-grown cultures had very low hydrolytic activity against either filter paper or crystalline cellulose (Avicel) as substrate, although H3PO4-swollen cellulose, carboxmethylcellulose, and cellobiose were readily hydrolyzed. Cells grown on either cellobiose or glucose exhibited cell-bound carboxymethylcellulase (CMCase) and cellobiase activities. Cultures grown on cellulose had seven to eight times more CMCase activity than either cellobiose- or glucose-grown cultures. Seventy percent of the CMCase activity was present in the supernate, of which 50--60% was associated with sedimentable membranous fragments. the cellobiase, which was largely cell associated, appeared to be constitutive, and the only product detected on enzymic hydrolysis of cellobiose was glucose. The cellobiase activity was strongly inhibited by 0.02 M tris(hydroxymethyl)-aminomethane (Tris), pH 7.1, but this was partially relieved by phosphate ions. These data indicate that B. succinogenes S-85 contains high endo-beta-1,4-glucanase and beta-1,4-glucanase and beta-1,4-glucosidase-like activities.