XYLANOLYTIC ENZYME SYSTEM OF RUMEN BACTERIUM Prevotella bryantii B14

Abstract

Prevotella spp. are recognised as one of the most numerous strictly anaerobic bacteria inhabiting the rumen. Potentially significant activities include the degradation of plant cell wall polysaccharides, starch, proteins and peptides. P. bryantii B14 is not cellulolytic but actively degrades hemicellulose xylan and carries multiple xylanase genes. Four regions encoding xylanase activity have been isolated, one of which encodes a previously isolated CMC-ase. Of the remaining regions, one encodes activities against p-nitrophenyl-b -xyloside and p-nitrophenyl-a -L-arabinofuranoside (genes xyn A and xynB). The gene xynC encodes another endoxylanase. SDS PAGE xylanograms revealed four endoxylanolytic bands at 29 kDa, 45 kDa, 66 kDa and 88 kDa. The majority of endoxylanase and CMC-ase activity was found in periplasmic cell fraction while most of the a -L-arabinofuranosidase and b -xylosidase activities were found in the crude membrane fraction. HPLC separation of periplasmic proteins by CIM DEAE 8 tubes resulted in partial isolation of CMC-ase and 66-kDa endoxylanase.

Keywords

• microbiology
• bacteria
• Prevotellabryantii
• enzymes
• xylanases
• rumen