Abstract:
Chemical pesticides have disadvantages such as high production costs, short persistence,
comparative low efficacy, development of resistance to toxin and causing ecological
damage. In order to obtain cheaper biopesticides, many locally available and inexpensive
agricultural/industrial byproducts have potential as culture media for Bacillus thuringiensis
Crystal protein production. In this study, cost-effective media were developed, based on
locally available raw materials namely legumes, potato, and whey. Optimization studies
indicate that pH 6.4-7.5 was best for sporulation and OD 600 was highest at 37 °C for all
isolates tested. The optical density, protein concentration yield, sporulation and Chilo
partellus larvicidal action were studied by growing bacterial strains in these waste product
and in comparison with the conventional medium (NYSM). Protein concentration yield of
27.60 μg/ ml, spore count of 5.60 × 108 and Chilo partellus larvicidal activity (LC50) of 78
μg/ l against first-instar larvae were obtained with a 72 h culture of this bacterium. Based
on media comparison between NYSM and other media, the legumes produced the highest
spore counts, followed by potato and then whey; and, differences between media treatments
were significantly different (P≤0.05). The SDS-PAGE profiles indicated that spore-crystal
product from each treatment consisted of proteins with molecular weights of approximately
110-120 kDa and 60-70 kDa, suggesting the presence of bacterial insecticidal protoxins.
Therefore the investigation suggests that legume, potato and whey-based culture media are
more economical for the industrial production of Bt Insecticidal Crystal Proteins.
