Medium optimization and in vitro antioxidant activity of exopolysaccharide produced by Bacillus subtilis

The present study involves medium formulation using an agro waste, cane molasses, as the carbon substrate that was used instead of sucrose, to produce exopolysaccharide from Bacillus subtilis. Plackett Burman design was applied to evaluate twenty selected components, from which cane molasses, yeast extract, CaCl2, NaCl were found to be significant for fermentation. To study the concentration of each component, response surface methodology experimental design was performed using central composite design. The response plots resulted in optimized conditions—Cane molasses-2.36%, Yeast extract-0.56%, NaCl–0.71%, CaCl2 — 0.05%—which yielded 4.92 g/L at 48 h, at a temperature of 37 °C, initial pH 7 under still conditions. Antioxidant activity of EPS on DPPH resulted in a reducing capacity of 61.19%, at a concentration of 0.8mg/ml, greater than standard, Vitamin C. The biopolymer could thus be an ecofriendly product which can be subjected to various industrial and pharmaceutical applications.