Development of a cost effective medium for production of bacillus thuringiensis bioinsecticide using food barley

Abstract

Genetically manipulated food barley, Hordeum vulgare L. var. valfajr, was compared to commercial-grade starch as carbon sources in groundnut and soybean based media for supporting growth, sporulation and delta-endotoxin production by Bacillus thuringiensis Berliner B. thuringiensis kurstaki HD-1 and a promising newly isolated B. thuringiensis strain (referred to as BTA) were used. MgCl 2, CaCl2, and MnCl2 were used as trace-elements. Culture media were compared in shaken flasks and then in 5 l Fermentors. Biomass, delta-endotoxin levels and the number of spores as colony forming units (CFU) were evaluated. For each of the two strains, biomass and delta-endotoxin synthesis were not significantly different in soybean-based media after substitution starch by barley flour. There were significant differences between the two strains with respect to biomass and toxin production. Evaluated costs of media preparation showed that food barley is an economical alternative to commercial-grade starch in the production of BTA bioinsecticide.