Production of xylo-oligosaccharides using a Streptomyces rochei xylanase immobilized on Eudragit S-100

Abstract

A xylanase from Streptomyces rochei L10904 was purified and characterized. The enzyme was enriched to apparent homogeneity by ammonium sulphate precipitation and CM Sepharose Fast Flow ion exchange, with an apparent molecular weight of 22.5 kDa. The purified xylanase was non-covalently immobilized on Eudragit S-100 in order to produce xylo-oligosaccharides, and found to retain at least 98.9% of its activity in this application. The immobilized xylanase exhibited a shift in optimal pH from 6.5 to 7.2 while the optimal temperature was increased from 65 to 70 °C. The half-time of immobilized xylanase was 50% higher than that of the free xylanase and the storage stability of the immobilized enzyme was also improved. The end-products produced from hydrolyzing a pre-treated bean stalk substrate were mainly xylobiose and xylotriose, and the total content of XOS (DP = 2 ∼ 5) was up to 85% for the immobilized xylanase after incubating at 50 °C for 24 h, without any xylose being detected. Immobilized xylanase retained about 60% of its initial catalytic activity after 5 successive cycles of hydrolysis.