Xylooligosaccharide production from lignocellulosic wastes with Trichoderma longibrachiatum xylanase

Xylooligosaccharide (XO) production was performed by enzymatic hydrolysis of xylans which were obtained by alkali extraction from tobacco stalk (TS), cotton stalk (CS) and wheat straw (WS). Xylan was hydrolyzed using Trichoderma longibrachiatum xylanase preparation, and the effects of pH, temperature, hydrolysis period, substrate and enzyme concentrations on the xylooligosaccharide yield and degree of polymerization were investigated. It was found that these three agricultural wastes contained different amounts of xylan, cellulose and lignin and the xylan obtained from these sources contained different amounts of sugar and uronic acid. The xylan from WS had the highest amount of arabinose while the other xylans mainly had xylose and small amount of glucose. Trichoderma longibrachiatum xylanase hydrolyzed highly branched wheat straw xylan (WSX) better than cotton stalk xylan (CSX) and tobacco stalk xylan (TSX) under favorable conditions ( reaction time of 8 h at pH 4.6 and 50oC). The TLC analysis of the hydrolysis products indicated that the hydrolysis product of T. longibrachiatum xylanase contained different amounts of oligosaccharides (X2, X3, X4, X5, X6, X7) with some monosaccharides. Regardless of the structural differences of the xylan types presented in this paper, all xylans generated XO with different degree of polymerization (DP).