Enhancement of lactic acid production from food waste through simultaneous saccharification and fermentation using selective microbial strains

The development of sustainable methods with robust strains and renewable substrates for the production of high-value chemicals has gained much attention recently. This study investigates the effect of ten different microbial strains for lactic acid production from food waste through simultaneous saccharification and fermentation process at optimal conditions of pH 5.5–6.5 at 30 °C. The highest lactic acid concentration of 18.69 g L-1 was obtained from Lacobacillus manihotivorans DSM 13343, followed by 17.03 g L-1 from Lactobacillus plantarum DSM 20174 and 15.88 g L-1 from mixed culture during fermentation of food waste, whereas the strains produced only 12.72 g L-1, 17.75 g L-1, and 9.38 g L-1 respectively from MRS broth, therefore showing that the food waste was a superior substrate compared to the MRS broth for lactic acid fermentation. The maximum lactic acid yield was 0.73 g g-1, 0.71 g g-1, and 0.69 g g-1 with Lacobacillus manihotivorans DSM 13343, Lactococcus lactis subsp. lactis DSM 20481, and Lactobacillus plantarum DSM 20174 respectively with high selectivity for lactic acid up to 84%. Furthermore, this study has achieved significant lactic acid production with increased substrate utilization in lower processing time and reactor volume.