[Expression of xylanase gene xynA from Streptomyces olivaceoviridis A1 in Escherichia coli and Pichia pastoris].

The gene xynA encoding xylanase was cloned from Streptomyces olivaceoviridis A1. The xynA with and without origin signal peptide sequence were fused behind pel B signal peptide in the plasmid pET-22b(+) respectively, then transfered into the host E. coli. The xylanase expressed in E. coli had normal bioactivity. Further, the xynA without origin signal peptide sequence was cloned into the plasmid pPIC9 under the control of AOX1 promoter and introduced into the host Pichia pastoris by electroporation. The results of SDS-PAGE and activity assay of the xylanase expressed by recombinant P. pastoris showed that the xynA had been overexpressed and secreted, and the xylanase expressed had normal bioactivity. The expression level of xylanase in recombinant P. pastoris exceeded 0.2mg/mL in shake culture.