Abstract: Studies on removing exo-β-xylosidase by ultrafiltration from xylanase synthesized by Trichoderma reesei Rut C-30 and production of xylo-oligosaccharides from xylan hydrolyzed by selectively purified xylanase were investigated. It was found that ultrafiltration could remove completely exo-β-xylosidase from xylanase system. The liquid of permeation of ultrafiltration was identified to be homogeneous by sodium dodecylsilfate-polyacrylamide gel electrophoresis (SDS-PAGE) chromatography, and the product of enzymatic hydrolysis from the liquid of permeation of ultrafiltration was wholly xylo-oligosaccharides. The yield of xylo-oligosaccharides increased from 26.83% to 54.22% when enzymatic hydrolysis time was increased from 2 h to 10 h. However, during the production of xylo-oligosaccharides from xylan hydrolyzed by coarse xylanases, the yield of xylo-oligosaccharides dropped from 17.97% to 11.12%, when enzymatic hydrolysis time was increased from 2 h to 10 h. It was concluded that the effective conversion of xylan was enhanced and the ratio of xylo-oligosaccharides to xylose was markedly increased with this method, and this teachnique would provide a new way for xylo-oligosaccharides production.

Key words: xylo-oligosaccharides, enzymatic hydrolysis, xylanase, Trichoderma reesei.