Isolation, Characterization and Detection of Cry Gene Contents from South Indian Isolates of Bacillus thuringiensis

Bacillus thuringiensis Berliner based bio pesticides have been successfully used worldwide for the control of agricultural pests and vectors of human diseases; constitutes a large family of bacterial subspecies highly specialized as insect pathogens found in many a different habitat, that is characterized by the production of insecticidal crystal proteins (Cry proteins or d-endotoxins that are encoded by cry genes). In this report, candidate B. thuringiensis isolates were recovered from environmental samples using a combination of a staining and reduced selection. Isolates were further characterized by light microscopy, PCR, SDS-PAGE, bioassay or transmission electron microscopy. Forty nine B. thuringiensis strains were isolated and characterized from 55 representative samples of southern states of India. Based on the SDS-PAGE patterns and the presence of cry genes or a crystal shows major bands of Cry1 type indicates that the isolates differed from each other, showing the usefulness of diversity studies. Characterization of putative isolates was based on PCR using lepidopteron specific primers showed that the 40 isolates indicating their effectiveness against lepidopteron pests. Preliminary toxicity studies showed that the 36 isolates were toxic to the larvae of Bombyx mori (Linnaeus). Characterisation of the putative novel strains provides the useful information about the distribution with native cry gene content.