Chandra Mohan Meena, T.H. Ashok, Sujeet Kumar and Kheta Ram Tak
Abstract
Bacillus thuringiensis is a Gram positive, rod shaped and spore forming bacterium, which produces crystal proteins (proteinaceous inclusions), called δ-endotoxins, that have insecticidal action. The present investigation was carried out to isolate B. thuringiensis from soils of different regions of Karnataka state, India. A total of 20 soil samples were collected and isolation of the B. thuringiensis strains was conducted. Initially, a total of 100 isolates which produced colonies like B. thuringiensis (cream coloured and fried egg like appearance of a on the plates) were selected. Then characterization of these isolates was done by microscopic studies (simple staining, gram staining, endospore staining and crystal staining) and biochemical tests (catalase test, starch hydrolysis and casein hydrolysis). After these microscopic and biochemical studies, out of 100 isolates only 39 isolates were characterized as B. thuringiensis. Out of 20 soil samples B. thuringiensis was isolated from 16 soil samples (80%). Four soil samples (20%) were not found to contain B. thuringiensis.