Recent Advances in Bacillus thuringiensis Formulations

Bacillus thuringiensis Berliner (Bt) based biopesticides are utmost importance and occupy almost 97% of the world biopesticide market. Bt is a Gram positive, spore forming bacteria that has insecticidal properties affecting a selective range of insect orders, namely, Lepidoptera, Diptera and Coleoptera. The final fermented Bt broth comprises of spores, cell debris, inclusion bodies, enzymes and other residual solids, which needs to be recovered efficiently. Key factors governing the choice of harvesting strategy include process throughput, physical characteristics of product and impurities and desired end-product concentration. Stabilizing adjuvants may have to be incorporated in postharvest operation to prevent spore mortality and/or germination. Various formulations of Bti have given higher rates of kill and sustained persistence in several cases, ranging up to two months in single application. Encapsulation in the form of microcapsules has been extensively exploited to give smaller size, highly efficient fungal biopesticide formulations.