Cloning, characterization, and expression of xylanase gene from Bacillus lyticus in Escherichia coli and Bacillus subtilis

A genomic library of Bacillus lyticus was constructed in, GEM 11 vector and screened for the xylanase gene using Congo red plate assay. A 16-kb fragme nt containing the xylanase gene was obtained which was further subcloned us ing Mbo I partial digestion in an E.coli pUC 19 vector. A 1.3-kb sub-fragme nt was obtained which coded for a xylanase gene of M(r)23,650 Da. This frag ment was sequenced and the homology was checked with known xylanases. The m aximum homology was 97%, which was obtained with an endo xylanase gene from Bacillus species at the DNA level, while the translated sequence showed on ly one amino acid change from alanine to serine at position number 102. Exp ression was checked in E.coli, using the native promoter, and an extracellu lar activity of 5.25 U/mL was obtained. Cloning of the gene was done in Bac illus subtilis using a shuttle vector pHB 201, which resulted in increasing the basal level xylanase activity from 14.02 to 22.01 U/mL.