Cost effective production of Bacillus thuringiensis subsp. israelensis using chemically pre-treated rice straw

Abstract

Bacillus thuringiensis subsp. israelensis is the leading biopesticide in the world due to its specificity and lack of toxicity. The use of Bti is still restricted in developing countries due to the bioprocess complications and high cost of production. In the present study we have shown that lignocellulosic agro waste residues like rice straw can be used as cost effective substrates with appropriate chemical treatment methods. We have shown that compared to untreated rice straw, pre-treated rice straw gives better biomass production, and also shows less sporulation time, which in turn gives reduced larval killing time as part of larvicidal assay. Sodium hydroxide (NaOH) has proven to be a better delignifying agent compared to Calcium hydroxide (CaOH). It is found that supplementation of the medium with the fish slurry enhances biomass production in the case of both NaOH and CaOH. This biomass enhancement is also visible when chicken feather hydrolysate is used as Nitrogen supplement, although it is not as effective as fish hydrolysate.