Cloning and characterization of xylanase A from the strain Bacillus sp. BP-7: comparison with alkaline pI-low molecular weight xylanases of family 11.

The xynA gene encoding a xylanase from the recently isolated Bacillus sp. strain BP-7 has been cloned and expressed in Escherichia coli. Recombinant xylanase A showed high activity on xylans from hardwoods and cereals, and exhibited maximum activity at pH 6 and 60 degrees C. The enzyme remained stable after incubation at 50 degrees C and pH 7 for 3 h, and it was strongly inhibited by Mn(2+), Fe(3+), Pb(2+), and Hg(2+). Analysis of xylanase A in zymograms showed an apparent molecular size of 24 kDa and a pI of above 9. The amino acid sequence of xylanase A, as deduced from xynA gene, shows homology to alkaline pI-low molecular weight xylanases of family 11 such as XynA from Bacillus subtilis. Analysis of codon usage in xynA from Bacillus sp. BP-7 shows that the G+C content at the first and second codon positions is notably different from the mean values found for glycosyl hydrolase genes from Bacillus subtilis.