Direct conversion of raw starch to lactic acid by Lactobacillus plantarum MTCC 1407 in semi- solid fermentation using sweet potato (Ipomoea batatas L.) flour

531-537Lactobacillus plantarum MTCC 1407 was used for direct fermentation of raw starch in sweet potato (Ipomoea batatas L.) flour (SPF) to lactic acid (LA) under semi- solid fermentation using Mann Rogassa Sharpe medium containing (3%) SPF in lieu of glucose (2%) as carbon source. Response Surface Methodology (RSM) was used to evaluate effect of incubation period, temperature and pH on LA production, using a full factorial Central Composite Design (CCD). At optimum parameters (incubation period, 120 h; temperature, 35°C and pH, 6.5), maximum starch conversion by Lb. plantarum MTCC 1407 to LA was 56.4%. The organism produced (L+) LA (23.86 g) from starch (55 g) present in SPF (100 g); LA production yield (mass LA produced mass starch present in SPF⁻¹ x 100) was 43.4%