Direct production of l(+)-lactic acid from starch and food wastes using Lactobacillus manihotivorans LMG18011

This study describes several essential factors for direct and effective lactic acid production from food wastes by Lactobacillus manihotivorans LMG18011, and optimum conditions for simultaneous saccharification and fermentation using soluble starch and food wastes as substrates. The productivity was found to be affected by three factors: (1) initial pH, which influenced amylase production for saccharification of starch, (2) culture pH control which influenced selective production of l(+)-lactic acid, and (3) manganese concentration in medium which improved in production rate and yield of lactic acid. The optimum initial pH was 5.0–5.5, and the fermentation pH for the direct and effective fermentation from starchy substrate was 5.0 based on the yield of l(+)-lactic acid. Under these conditions, 19.5 g l(+)-lactic acid was produced from 200 g food wastes by L. manihotivorans LMG18011. Furthermore, the addition of manganese stimulated the direct fermentation significantly, and enabled complete bioconversion within 100 h.