Molecular cloning and characterization of exochitinase a gene of indigenous Bacillus thuringiensis isolates

Chitin is a naturally occurring insoluble linear β1-4 linked polymer of n-acetylglucosamine and a common constituent of the fungal cell wall and exoskeleton of arthropods. chitinases convert chitin into its economically important derivatives. in the present study,13 bacillus thuringiensis (bt) isolates screened on colloidal chitin medium were found to have chitinolytic activity. the maximum chitinase activity (0.23±0.001 u/ml) was shown by cmbl-bt4 after 4 days of incubation at 37°c (ph 7.0). sbs-bt1,3,5 and 6 were found positive for chitinase (chi) gene. the amplified genes were cloned in ptz57r ta cloning vector,sequenced and submitted to embl with accession nos. hg792449 to 52. all these genes,had 99% homology with bacillus cereus chia (ab041931.1) and bacillus cereus strain 49 chia (gu134904.1),and 97% similarity with bacillus thuringiensis ybt-1518 strain (cp005935). the structure of exochitinase predicted by phyre2 showed 107ggqng111,141ddle145 and 225qhyn228,regions,respectively for chitin binding,catalysis and substrate hydrolysis. the exochitinasea genes described in this study can be employed in vast applications including the production of transgenic plants and in bringing out commercial formulation for the control of lepidopteran pests. copyright 2014 zoological society of pakistan.