Optimum conditions for the biological production of lactic acid by a newly isolated lactic acid bacterium,Lactobacillus sp. RKY2
Lactic acid is a green chemical that can be used as a raw material for biodegradable polymer. To produce lactic acid through microbial fermentation, we previously screened a novel lactic acid bacterium. In this work, we optimized lactic acid fermentation using a newly isolated and homofermentative lactic acid bacterium. The optimum medium components were found to be glucose, yeast extract, (NH4)2HPO4, and MnSO4. The optimum pH and temperature for a batch culture ofLactobacillus sp. RKY2 was found to be 6.0 and 36°C, respectively. Under the optimized culture conditions, the maximum lactic acid concentration (153.9 g/L) was obtained from 200 g/L of glucose and 15 g/L of yeast extract, and maximum lactic acid productivity (6.21 gL−1h−1) was obtained from 100 g/L of glucose and 20 g/L of yeast extract. In all cases, the lactic acid yields were found to be above 0.91 g/g. This article provides the optimized conditions for a batch culture ofLactobacillus sp. RKY2, which resulted in highest productivity of lactic acid.
Keywordsbatch fermentation culture conditions homofermentation lactic acid Lactobacillus
- Miura, S., L. Dwiarti, T. Arimura, M. Hoshino, L. Tiejun, and M. Okabe (2004) Enhanced production ofl-lactic acid by ammonia-tolerant mutant strainRhizopus sp. MK-96-1196.J. Biosci. Bioeng. 97: 19–23.Google Scholar
- deMan, J. C., M. Rogosa, and M. E. Sharpe (1960) A medium for the cultivation of lactobacilli.J. Appl. Bacteriol. 23: 130–135.Google Scholar
- Stainer, R. Y., J. L. Ingraham, M. L. Wheelis, and P. R. Painter (1986)The Microbial World. 5th ed., pp. 495–504. Prentice Hall, NY, USA.Google Scholar
- Åkerberg, C., K.Hofvendahl, G. Zacchi, and B. Hahn-Hägerdal (1998) Modeling the influence of pH, temperature, glucose and lactic acid concentrations on the kinetics of lactic acid production byLactococcus lactis ssp.lactis ATCC 19435 in whole-wheat flour.Appl. Microbiol. Biotechnol. 49: 682–690.CrossRefGoogle Scholar