Improvement of the catalytic characteristics of a salt-tolerant GH10 xylanase from Streptomyce rochei L10904.

A GH10 xylanase Srxyn10 from Streptomyce rochei L10904, and its truncated derivative, Srxyn10M, were investigated. Both displayed great salt-tolerant ability, retaining more than 95% and 91% activity after incubation at 37°C for 1h in 3.0M and 5.0M NaCl, respectively. They exhibited a special hydrolytic property of forming xylobiose as the major product and produced fewer xylose compounds when combined with a reported xylanase while digesting corncob xylans. The mutant, Srxyn10M, was constructed from Srxyn10 by deleting the C-terminal carbohydrate-binding module. It possessed a 3.26-fold higher specific activity on beechwood xylan than Srxyn10. Moreover, Srxyn10M showed greater substrate affinity and catalytic efficiency than Srxyn10 when beechwood xylan, birchwood xylan, and oat-spelt xylan were used as substrates. The thermostability was also greatly improved. Therefore, the application potential was markedly enhanced by the improvement of these properties.