DEVELOPMENT OF LOW COST MEDIA BY USING AGRO BASED BY-PRODUCTS FOR THE PRODUCTION OF AN INDIGENOUS ISOLATE OF BACILLUS THURINGIENSIS VAR. KENYAER.S. HIRE, N. VIJAYALAKSHMI AND T.K. DONGRE
The media based on agro-based by-products in different combinations were investigated for their ability to support the growth, sporulation and larvicidal activity of our indigenous isolate, Bacillus thuringiensis var kenyae. Media based on molasses, corn steep liquor and mushroom extract supported the growth and sporulation of B. thuringiensis var kenyae. The corn steep liquor based medium was found to be the most suitable one amongst the various media tried. The yield in terms of lyophilized powder in standard nutrient broth medium was 2.08 gm/liter with total viable count of 1.95 x 10" spores/gm, whereas yield in medium based on corn steep liquor was 6.90 gm/liter with a total viable count of 1.5 x1011 spores/gm. The scale up studies were carried out in 20-liter capacity fermentor. Fermentor batches using nutrient broth medium as well as corn steep liquor based medium exhibited comparable toxicity to the larvae of test insects, Earias vittella and Spodoptera litura. The total cost of the medium required for the production of Bt based biopesticide can be reduced significantly by replacing nutrient broth with the corn steep liquor or mushroom extract.
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