Bacillus spp. in the rumen ecosystem. Hemicellulose depolymerases and glycoside hydrolases of Bacillus spp. and rumen isolates grown under anaerobic conditions

Bacillus spp. were isolated from the rumen contents of animals fed on hay. The bacilli were present in the vegetative form in the microbial populations of the liquid phase and in those associated with the particulate material in the digesta. Thirty-six isolates were identified as strains of B. licheniformis (14), B. circulans (14), B. coagulans (2), B. laterosporus (3) and three isolates were facultative anaerobes that resembled B. pumilus. All were able to utilize isolated Lolium perenne hemicellulose B as a carbon source when grown aerobically or anaerobically at 39°C. A survey of 17 Bacillus species (24 strains including 5 rumen isolates) confirmed that enzymes capable of releasing reducing sugars from hemicelullosic polysaccharides were present in many anaerobically grown bacilli; in addition, the range and specific activities of 20 glycoside hydrolases were also monitored in these crude enzyme preparations. The presence and possible role of Bacillus spp. in the rumen digesta particle-associated microbial population is discussed.