Abstract

This study aims is to characterize an efficient bacterium, capable of producing thermostable xylanases. Different bacterial isolates were obtained on medium containing xylan as the sole carbon source from samples collected from Jeddah, Saudi Arabia. Out of 15 xylanase producing isolates, the best xylanase producer was XP10 which was selected for the enzyme production. It was identified based on morphological and some biochemical characters as a species belonging to the genusBacillus and identified as Bacillus subtilis XP10. Identification was confirmed by 16S rDNA studies and restriction fragment length polymorphism. Factors affecting enzymes production were studied. Maximum xylanase production was 2.82 U/ml obtained at pH 8 for 4 days at 40°C and 120 rpm. The molecular weight of the purified enzyme was 23 kDa. Fivefold increasing in xylanase production was obtained by construction of recombinant Escherichia coli 107 harboring recombinant vector pJET1.2/blunt/xynA. The purified thermostable alkalotolerant xylanase can be used in the treatment of agricultural wastes as well as in the bioremediation of xylan-containing materials.

Key words: Xylanase, polymerase chain reaction based restriction fragment length polymorphism (PCR-based RFLP), 16S rDNA, sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS PAGE), xynA gene.

Abbreviation

XB, Xylan broth; PCR, polymerase chain reaction; SDS-PAGE, sodium dodecylsulfate–polyacrylamide gel electrophoresis.