Optimization of Fermentation Conditions for Producing Exopolysaccharides by L. Bulgaricus Strain AK-1

Abstract

Exopolysaccharides (EPS) derived from lactic acid bacteria play a crucial role in antitumor activity, immunomodulation bioactivity. With MRS as lactobacillus basic culture, the high yield of EPS by lactobacillus bulgaricus strain AK-1 optimized fermentation condition was analyzed in this paper. The optimum pH, volume, fermentation time, carbon sources, nitrogen, and microelement were studied by single factor experiment. The orthogonal test was used for seed volume, fermentation temperature and fermentation time. The results showed that the optimum medium was including 35 g/L Glucose based on MRS culture, the optimum inoculum size was 2%, initial pH was 5.3, the optimum temperature was 40°C, and fermentation time was 8 hours. The yield of EPS is 409mg/L under the optimum condition, more than that in reported value (354mg/L).