Characterization of Chitinases from Bacillus thuringiensis strains

The present study was conducted to characterize the Chitinase enzyme from Bacillus thuringiensis strains.13 strains of Bacillus thuringiensis were screened. All strains were found to have chitinolytic activity. The chitinolytic strains were screened for maximum activity at varying pH. Chitinase activity was assayed as the amount of N-acetylglucosamine released in U/ml using the DNS assay method. The maximum activity (0.229±0.001 U/ml) was shown by CMBL-Bt4 after 4 days of incubation at 37 C (pH 7.0) when medium was supplemented with 1% colloidal chitin. PCR was employed to amplify the chitinase gene from SBS-Bt1, SBS-Bt3, SBS-Bt5 and SBS-Bt6 by using a specific pair of primers. The amplified gene was then cloned into pTZ57R TA cloning vector and transferred in E.coli. The sequenced genes of SBS-Bt1, SBS-Bt3, SBS-Bt5 and SBS-Bt6 consist of 1195, 1103, 1212 and 1150 nucleotides respectively encoding 360 residues. The calculated molecular weight of SBS-Bt1, 3 and 5 was 39.47kDa while that of SBS-Bt6 was 39.39kDa and pI value of 6.95. The chi gene sequences of the studied strains shows 90% similarity with Bacillus thuringiensis serovar colmeri chiA (EF103273.1)