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United States Department of Agriculture

Agricultural Research Service

Title: Isolation and Characterization of a Xylanolytic Bacterium Capable of Fermenting Corn Fiber Xylan

item Zeltwanger, Rhonda

Submitted to: Society of Industrial Microbiology Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: August 7, 1997
Publication Date: N/A

Technical Abstract: Wet milling of corn generates about 2.8 million tons of corn fiber, a xylan rich residue of the food and fuel alcohol industries. Utilization of this and similar xylan containing residues could improve the economics of the industrial processes that result in their production. Xylan is readily fermented in anaerobic microbial ecosystems like the rumen, and microorganisms from these environments may serve as rich sources of xylan degrading enzymes. Corn fiber xylan (CFX) containing ruminal enrichment cultures were established and after several transfers, xylanolytic bacteria were isolated on RBB dyed xylan agar medium. One isolate was able to grow rapidly in CFX containing medium, utilizing greater than 90% of the substrate (2.5 mg/ml) in less than 8 h. This strain, RZ, is a strictly anaerobic, Gm-, pleomorphic, rod-shaped bacterium phenotypically similar to Prevotella ruminicola, but only possessed 87% 16s rRNA gene sequence identity with the type strain of P. ruminicola. In addition to CFX, strai RZ also utilized xylans isolated from a variety of plant sources. Xylosidase and high levels of arabinosidase activity were produced by strain RZ, but little xylanase activity could be detected with whole cells or in extracellular culture fluids. Only following cell disruption by french pressure cell treatment were measurable levels of xylanase activity detected. Strain RZ may sequester hydrolytic enzymes in the periplasm like other Bacteroides and Prevotella species.

Last Modified: 4/22/2015