PRODUCTION OF BACILLUS-THURINGIENSIS BERLINER VAR. KURSTAKI GROWN IN ALTERNATIVE MEDIA

Agro-industrial residues and by-products available in southeastern Bra zil were used as ingredients for low-cost culture media for liquid fer mentation of Bacillus thuringiensis var. kurstaki. Highest spore yield was obtained with a medium containing cheese whey, soya bean milk and molasses (WSM). Crystals and spores were produced in all media and po tency of the final product was highest for nutrient broth+yeast extrac t medium (NBY). There was no correlation between the number of spores in the fermented media and the potency of the preparations. Considerin g all three factors, the potencies, costs and yields of the final prod ucts, lowest relative cost was obtained with BMM medium (Bombyx mori p upae+molasses). NBY and WSM had intermediate relative cost approximate ly nine times higher than BMM. The cost analysis suggests that BMM med ium should by preferred for local production of B. thuringiensis var. kurstaki in comparison to other media tested. The results also demonst rate the importance of considering yields, cost and potency of the B. thuringiensis preparations in selecting the production medium.