Abstract: In this study, an alkaliphilic strain (HSL38) producing xylanase was isolated from mangrove soil, and identified as Bacillus halodurans C-125 (GenBank: NC_002570.2) based on 16S rDNA analysis, which revealed a similarity of 99%. Specific primers based on theβ-1,4-xylanase gene xynA of Bacillus halodurans C-125 were designed, and theβ-1,4-xylanase gene (xyl-BH-G10) from HSL38 strain was amplified. Sequence analysis showed 99% similarity between the xynA gene and the amplified gene encoding a precursor of 396 amino acid residues (45.27 kD), which belonged to glycoside hydrolase family 10 GH10. A recombinant expression plasmid was constructed by linking xyl-BH-G10 to the expression plasmid pET-30a-c(+), and then transformed into E. coli BL21(DE3). The expression of recombinant protein was achieved under IPTG induction. These investigations indicated that theβ-1,4-xylanase gene xyl-BH-G10 was highly expressed in E. coli BL21 (DE3) cells under the optimal induction conditions, and an xylanase activity of 55.28 U/mL was obtained, which exhibited a 4-fold enhancement when compared to the fermentation of original HSL38 strain.  

Key words: Bacillus halodurans, xylanase, cloning, expression