Production of L(+) lactic acid by Lactobacillus amylophilus GV6 in semi-solid state fermentation using wheat bran

Lactobacillus amylophilus GV6 was used for direct fermentation of raw starch in wheat bran to L(+) lactic acid in semi-solid state fermentation. At m/V ratio of wheat bran 9 % (9 g of wheat bran in 100 mL of medium) with m/V ratio of CaCO₃ 0.375%, 2.5 g of L(+) lactic acid was produced. To maximize the production of lactic acid, process variables like the volume of inoculum and incubation period were optimized keeping m/V ratio of wheat bran and CaCO₃ at 9 and 0.375%, respectively, and constant pH=6.5, using response surface method (RSM). The organism produced 3.5 g of L(+) lactic acid from 3.96 g of starch present in 9 g of wheat bran. Maximum starch conversion to lactic acid was observed at process conditions of wheat bran m/V ratio 9% at 37°C, pH=6.5, inoculum volume 3.5 mL and incubation period of 130 h.