Biochemical characterization of a novel GH43 family β-xylosidase from Bacillus pumilus

Although β-xylosidases have a wide range of applications, cold-active β-xylosidases have been poorly studied. In this study, a cold active β-xylosidase gene (xyl) from Bacillus pumilus TCCC 11,350 was cloned and overexpressed in Escherichia coli. The recombinant XYL (rXYL) was revealed to be a bifunctional enzyme with both β-xylosidase and α-l-arabinofuranosidase activities. Purified rXYL was most active at 30 °C, demonstrating 26% and 18% of its maximum activity at 4 °C and 0 °C, respectively. Meanwhile, rXYL showed a 52% activity in 200 mM xylose, indicating a relatively strong tolerance to xylose. Moreover, rXYL exhibited a high synergistic effect (11.14-fold and 16.21-fold) with endo-xylanase to degrade beechwood xylan in both sequential and simultaneous reactions at low temperatures. As the first report on the novel cold-adapted β-xylosidase from B. pumilus, these results suggested rXYL had attractive properties for food industrial utilizations.