Isolation of genes encoding β-D-xylanase, β-D-xylosidase and α-L-arabinofuranosidase activities from the rumen bacterium Prevotella ruminicola B(1)4

Prevotella ruminicola B14 is a strictly anaerobic, Gram-negative, polysaccharide-degrading rumen bacterium. Xylanase activity in this strain was found to be inducible, the specific activity of cells grown on xylan being increased at least 20-fold by comparison with cells grown on glucose. Ten bacteriophage clones expressing xylanase activity were isolated from a A EMBL3 genomic DNA library of P. ruminicola B14. These clones were shown to represent four distinct chromosomal regions, based on restriction enzyme analysis and DNA hybridisation. Three groups of clones encoded activity against oat spelt xylan but not carboxymethylcellulose (CMC). In one of these groups, represented by clone 5, activities against pNP-arabinofuranoside and pNP-xyloside were found to be encoded separately from endoxylanase activity. The fourth region encoded activity against CM cellulose and lichenan, in addition to xylan, and contains an endoglucanase/xylanase gene isolated previously.