Other species of Gram-positive cellulolytic rumen bacteria are known to include Eubac — terium cellulosolvens (32,33). Some strains of Butyrivibrio fibrisolvens have also been reported to be cellulolytic, although most strains of this species are actively hemicellulolytic, but not cellulolytic (34-36). Interestingly, there is evidence for cell-associated enzyme complexes in B. fibrisolvens (37). Sortase-mediated anchoring of individual enzymes to the bacterial cell wall has also been reported for amylases from a human colonic B. fibrisolvens strain and from the related Roseburia inulinivorans (38). It is likely, however, that many other species whose primary niche is not in plant cell wall breakdown possess enzymes for the transport and utilization of oligosaccharides released from plant cell walls. Selenomonas ruminantium, for example, has a xylan utilization operon (39) and is involved in interactions with cellu­lolytic species (40). Even Streptococcus bovis, assumed to be primarily a starch-degrading species, was found to possess a mixed link p-glucanase (41). The role of this enzyme was postulated to be in gaining access to starch through the removal of p-glucan-rich walls of cereal endosperm cells.