Optimization of Biosynthesis Conditions for the Production of Exopolysaccharides by SP8 and the Exopolysaccharides Antioxidant Activity Test.

SP8, isolated from traditional Chinese pickle juice, was utilized for the production of exopolysaccharides (EPSs), but the EPS yield was low under normal MRS medium. The single factor experiment and response surface methodology were used to optimize the medium components and culture conditions and the optimal conditions for EPS production were successfully obtained. Results showed that the optimum condition was glucose 22 g/L, yeast extract 30 g/L, fermentation temperature 35.6 °C, fermentation time 22 h and the theoretical EPS yield was 282.494 mg/L. The results were similar to the actual yield, 280.105 mg/L. By optimizing the culture conditions, the yield of SP8 EPS was improved by nearly 19 times. In the gas chromatography analysis, it was found that SP8 EPS consisted of d-rhamnose, arabinose, galactose, and d-acetylglucosamine, but glucose was not included, which was quite different from the reported heteropolysaccharide component of . Furthermore, the antioxidant activity of SP8 EPS was evaluated with the in vitro scavenging abilities on DPPH·, and ·OH. The in vitro antioxidant activity study indicated that SP8 EPS possessed certain antioxidant activity. All results demonstrated the potential of SP8 in the food and dairy industry.