Molecular cloning and expression of xylanases from an alkalophilic thermophilic Bacillus (NCIM 59) in Bacillus subtilis A8

The 6.5-kb Hind III fragment of alkalophilic-thermophilic Bacillus genomic DNA, coding for two xylanases, was cloned from Escherichia coli recombinant plasmid pATB X235 in a Bacillus plasmid pLP1202 at the Hind III site, inactivating the tetracycline resistance gene. Bacillus subtilis A8 was transformed with the ligation mixture using electroporation. Ninety-five percent of the enzyme activity was extracellular. The xylanases produced by the recombinant showed molecular weights of 35 and 14.5 kDa. The hydrolysis of xylan by the recombinant xylanases yielded mainly xylobiose. Xylose was also detected, along with traces of xylotriose and xylotetrose.