Evaluation of a cereal milling by-product for the low cost production of Bacillus thuringiensis kurstaki in submerged fermentation

With the idea of finding a cheap medium for the mass production of Bacillus thuringiensis (Bt), a cereal milling by product (CMB) was evaluated and was shown efficient to be used as a source of carbohydrates, proteins and minerals for the production of δ-endotoxins in submerged fermentation of a new strain of Bacillus thuringiensis kurstaki “Lip”. The results obtained in 1000 mL shake flasks experiments showed that the toxin proteins concentration produced in the 6% (w/v) CMB medium was 2.4 fold and 1.54 fold greater than the values reached in the Anderson medium and in a standard semi synthetic medium respectively, while there was no significant difference between the cell, spore and crystal counts or between the protein profiles of the “Lip” spore/crystal complex obtained in the three mediums. Considering all three factors, relative yield, productivity and cost, the use of the CMB mono-component medium was proved much more economical for an industrial production of “Lip” than the references mediums. Moreover, the suitability of the medium for large scale production of Bt based bio insecticide was evidenced in a 5 L lab bioreactor