Influence of amino nitrogen in the culture medium enhances the production of δ-endotoxin and biomass of Bacillus thuringiensis var. israelensis for the large-scale production of the mosquito control agent

Abstract

We reported here the role of amino nitrogen in the commercial production of Bacillus thuringiensis var. israelensis media design. The insect pathogen B. thuringiensis var. israelensis was cultured in different media containing varying initial levels of amino nitrogen sources obtained from three different commercial venders. The biomass, mosquito larval toxicity and spore count produced were measured during the fermentation process. The results showed that the higher level of initial amino nitrogen concentrations in the medium led to higher yield of biomass (dry weight 4.78 g l⁻¹), larvicidal activity (LC₅₀ 18.52 ng ml⁻¹) and spore count (3.24 × 10¹¹ CFU ml⁻¹). Similarly decreasing the initial amino nitrogen concentration in the medium led to a decreased biomass (dry weight 1.64 g l⁻¹), larvicidal activity (LC₅₀ 27.01 ng ml⁻¹) and spore count (3.7 × 10¹⁰ CFUml⁻¹).