Expression and characterization of a novel endo-1,4-β-xylanase produced by Streptomyces griseorubens JSD-1 isolated from compost-treated soil

Abstract

Streptomyces griseorubens JSD-1 is an isolate sourced from compost-treated soil that can utilize xylan as the unique carbon source for growth; xylanlytic genes related to this process were expected to be crucial. However, little is known about the genetic basic of utilizing xylan in this isolate. To further investigate the molecular mechanism of xylan metabolism, genome sequencing was carried out. The draft genome obtained has been deposited with GenBank. Endo-1,4-β-xylanase (Xyn) was acquired, followed by characterization of its cellular localization and expression profiles. Xyn proved to be a novel enzyme, differing from xylanases from similar species according to combined analyses from multiple sequence alignments and putative three-dimensional structure modeling. Moreover, recombinant expression was optimized in heterogeneous hosts to further determine optimum pH and temperature conditions as well as residual activity in the presence of metal ions and inhibitors. Finally, substrate specificity and kinetic parameters were also studied. In conclusion, our findings illustrate the genetic background related to xylan metabolism in this isolate. In addition, a novel Xyn that is expected to have potential in the bio-degradation of hemicellulosic materials was expressed, purified and characterized.