ARS | Publication request: IDENTIFICATION OF A BIFUNCTIONAL XYLOSIDASE/ARABINOSIDASE IMPORTANT FOR XYLOOLIGOSACCHARIDE FERMENTATION BY THE RUMINAL ANAEROBE SELENOMONAS RUMINANTIUM GA192

Submitted to: Australian Society for Microbiology
Publication Type: Abstract Only
Publication Acceptance Date: October 3, 1997
Publication Date: N/A

Technical Abstract: Xylan is an abundant polysaccharide in plant cell walls and, as such, comprises a significant portion of the diets of ruminant livestock. The enzymatic hydrolysis of xylan is accompanied by the formation of xylose, arabinose, and methyl-glucuronic acid containing oligosaccharides. These oligosaccharides can be utilized by several species of xylanolytic ruminal bacteria and Selenomonas ruminantium, a non-xylanolytic species. The objective of this study was to examine the fermentation of xylooligosaccharides by strains of S. ruminantium and determine the enzymes and genes that may be important in the utilization of xylooligosaccharides by this organism. Strains of S. ruminantium varied in their capacity to ferment xylooligosaccharides. The ability of S. ruminantium strains to utilize xylooligosaccharides was correlated with the presence of xylosidase and arabinosidase activities. A genetic locus from S. ruminantium GA192 was isolated and sequenced that produced both xylosidase and arabinosidase activities in Escherichia coli. Analyses indicated that a single protein was responsible for both activities in S. ruminantium GA192 and the E. coli clone. The enzyme expressed in E. coli was capable of degrading xylooligosaccharides. Attempts are underway to introduce the cloned gene into S. ruminantium strains.