Cellodextrin utilization and beta-glucosidase production by Bacteroides polypragmatus.

Bacteroides polypragmatus, a mesophilic obligate anaerobe, was shown to simultaneously ferment glucose and cellobiose giving ethanol as a major metabolic end-product. A mixture of higher cellodextrins was also utilized. The bacterium produced a beta-glucosidase with a pI value of 4.2 and a molecular weight of approximately 100,000 daltons. The enzyme was intracellular and functioned optimally at pH 7. The Km values obtained with p-nitrophenyl-beta-D-glucoside and cellobiose as substrates were 0.73 mM and 100 mM, respectively. The enzyme was quite stable at elevated temperatures; in the presence of 10% glycerol (v/v), it had a half-life of 4 h at 55 degrees C. It was also stable during long-term storage at either 4 degrees C or -20 degrees C, provided that 10% (v/v) glycerol was added to preparations maintained at -20 degrees C.