Improvement in xylooligosaccharides production by knockout of the - gene in EU7-22.

The goal of this study was to enhance the production of xylooligosaccharides (XOs) and reduce the production of xylose. We investigated β-xylosidases, which were key enzymes in the hydrolysis of xylan into xylose, in EU7-22. The binary vector pUR5750G/:: was constructed to knock out the - gene (encoding β-xylosidases) in EU7-22 by homologous integration, producing the mutant strain Bxyl-1. Xylanase activity for strain Bxyl-1 was 452.42 IU/mL, which increased by only 0.07% compared to that of parental strain EU7-22, whereas β-xylosidase activity was 0.06 IU/mL, representing a 91.89% decrease. When xylanase (200 IU/g xylan), produced by EU7-22 and Bxyl-1, was used to hydrolyze beechwood xylan, in contrast to the parental strain, the XOs were enhanced by 83.27%, whereas xylose decreased by 45.80% after 36 h in Bxyl-1. Based on these results, Bxyl-1 has great potential for application in the production of XOs from lignocellulosic biomass.