Studies on production of lactic acid from various wastes using lactobacillus rhamnosus and lactococcus lactis subsp lactis

Lactic acid can be produced by fermentation of organic matters present in various wastes with the addition of various carbon and nitrogen sources using Lactobacillus species. Organic wastes form kitchen garbage and foodprocessing industries are especially rich in carbon and moisture content. The present study investigates the treatment of the organic wastes using microbiological process for effective usage of waste and to develop value added products from it. The organic wastes used in this processes are domestic wastes, vegetable wastes, fruit wastes, bakery wastes and whey. The microorganisms used in the synthesis of lactic acid are Lactobacillus rhamnosus and Lactococcus lactis subsp lactis. The fermentation study includes the effect of various wastes, effect of carbon and nitrogen sources with optimal waste medium, various concentrations of optimal carbon and nitrogen source and effect of time for free cells and their immobilized form on lactic acid production and biomass growth for both the organisms. The optimal production of lactic acid was determined as 35.45 g/l and bacterial growth was 1.34 g/l from whey by Lactobacillus rhamnosus. Optimal carbon source was mannitol, which yields 38.3 g/l of lactic acid and 1g/l of microbial growth. The study on effect of various concentrations of mannitol resulted a higher yield of lactic acid production at a concentration of 12 g/l with the production of 40.85 g/l. whereas the biomass yield was about 1.12 g/l at this optimum concentration.12g/l of peptone as nitrogen source effectively yields 53.5g/l of lactic acid and cell growth of 1.56 g/l. The results are promising for higher yield of lactic acid to be produced using Lactobacillus species compared to Lactococcus lactis subsp lactis.