Selective inactivation of spores maintaining larvicidal activity in Bt serovar israelensis irradiated with gamma rays

Abstract

Bacillus thuringiensis is used to produce biopesticides against target-insects of importance in agroindustry and human health. However, B. thuringiensis can carry the same enterotoxin-encoding genes as Bacillus cereus, suggesting a potential risk of food poisoning. The objective of this work was to study the application of gamma radiation to eliminate spores in biopesticides based on B. thuringiensis serovar israelensis in order to avoid the liberation of these spores in the environment. The application of 20 kGy of radiation ensures total inactivation of the spores in the insecticide without changing the larvicidal activity. Results showed that it is possible to develop formulations containing B. thuringiensis serovar israelensis (IPS-82) eliminating viable spores with gamma radiation without affecting the larvicidal activity. Irradiated formulations would be safer for the environment and humans since the elimination of viable spores abolishes the pathogenic potential of B. thuringiensis strains.