Biopesticide and formulation processes based on starch industrial wastewater fortified with soybean medium
Abstract The aim of this study was to produce Bacillus thuringiensis-based biopesticide using starch-producing industry wastewater (SIW) fortified with soybean medium and optimize the formulated product using different adjuvants. This study was necessary as low endotoxin concentration is obtained in formulated biopesticide when SIW alone is used as fermentation medium. The fermentation runs were conducted using SIW alone and SIW fortified with 25% soybean (w/v) medium in 2000 L and 150 L bioreactor, respectively. SIW supplemented with soybean medium showed an increase in cell count (from 1.95 × 108 to 1.65 × 109 CFU mL–1), spore synthesis (from 1.5 × 108 to 1.35 × 109 CFU mL–1) and endotoxin concentration (from 436 to 1170 μg mL–1) when compared to SIW medium alone. The fermented broth was concentrated using continuous centrifugation and adjuvants were added for biopesticide formulation in order to enhance its resistance against UV rays and rainfastness. Entomotoxicity of the formulation produced using fermented broth of SIW fortified with soybean (38,000 IU μL–1) was higher than that obtained by SIW medium alone (21,000 IU μL–1), commercial biopesticide Foray 76B (20,000 IU μL–1) and Btk sander’s (12,500 IU μL–1).