Biochemical characteristics of the mutant xylanase T-XynC(122)C(166) and production of xylooligosaccharides from corncobs

Abstract

The thermostable recombinant xylanase, T-XynC(122)C(166), was investigated for its biochemical characteristics and capacity to produce xylooligosaccharides from corncobs pretreated through auto-hydrolysis. T-XynC(122)C(166) showed optimal activity at pH 6.5 and 75 °C, and is an acidophilic and thermostable xylanase with a Km of 6.08 mg/mL towards beechwood xylan. Hydrolysis of xylan into xylooligosaccharides was through an endohydrolytic mode of action. Although xylotriose and xylobiose were the main hydrolysates produced from different xylans by T-XynC(122)C(166), their compositions and yields were substrate dependent. T-XynC(122)C(166) showed the highest degradation efficiency towards beechwood xylan, followed by oat-spelt xylan and birchwood xylan. T-XynC(122)C(166) rapidly hydrolyzed xylotetraose into xylotriose and xylobiose through transglycosylation, whereas xylotriose was hydrolyzed slowly and xylobiose was not hydrolyzed. The xylooligosaccharide yield from corncobs was determined to be 26.4% when treated with T-XynC(122)C(166) (5 U/mL) at pH 5.5 and 50 °C for 2 h, indicating its high potential for xylooligosaccharide production from agricultural waste.