Bacillus thuringiensis strains from Western Ghats of India possess nematocidal property against Haemonchus contortus larvae of goats.

Nematocidal properties of spore crystal mixtures of six Bacillus thuringiensis (Bt) strains (KAU 49, 50, 52, 61, 99 and 424) collected from Western Ghats, a biodiversity hot spot of India, were analysed against Haemonchus contortus larvae isolated from goats. One dose nematocidal assay dose response to lyophilised spore-crystal mixtures (SCM) of the six Bt strains were determined by adding 200 µg/mL of each SCMs to culture plate wells containing aqueous suspension of H. contortus larvae. Out of the strains screened, KAU 50 and 424 were found to possess nematocidal properties. Maximum nematocidal properties were exhibited 7 days post-inoculation of the lyophilised SCMs. The 50 per cent lethal concentrations deduced by log probit analysis for KAU 50 was found to be 130.59 µg/mL, whereas that of KAU 424 was found to be 144.536 µg/mL at 95 per cent confidence level. This is the first report on the nematocidal propery of Bt strains against Haemonchus contortus larvae isolated from goats. Further studies are needed for identification and characterisation of the toxin.

Crystal Protein of a Novel Bacillus thuringiensis Strain Inducing Cell Cycle Arrest and Apoptotic Cell Death in Human Leukemic Cells.

Parasporal inclusions of a native non haemolytic Bacillus thuringiensis strain KAU 59 was screened for its cytotoxicity against human lymphocytic leukemic cell line jurkat and normal human lymphocytes. The cytotoxicity of proteinase activated and non activated solubilised parasporal inclusions against both cell lines was assessed by Cell Titer 96 Aqueous Non Radioactive Cell Proliferation Assay Kit using MTS. The 50 per cent effective concentration (EC50) values were deduced from log probit analysis at 48 h. Morphological changes associated with cytotoxicity were evaluated and molecular mechanisms of cell death were elucidated by TUNEL assay at 48 h post-inoculation. The fluorescence assisted cell sorting was done in the flow cytometer to assess the stage of cell cycle arrest. Relative quantification of caspase-3 expression in Jurkat cells treated with parasporal inclusion protein of KAU 59 was done by qRTPCR The results indicated that the protein was cytotoxic to jurkat cells at the same time non toxic to normal lymphocytes. Cytotoxicity was evident only after proteolytic activation. Apoptotic cell death was confirmed in the protein treated cells by TUNEL Assay and also up regulated caspase-3 gene expression (P < 0.001). S phase cell cycle arrest was confirmed by and fluorescence associated cell sorting.