柠檬明串珠菌TD1产胞外多糖条件的响应面法优化及其抗氧化性研究

以柠檬明串珠菌（Leuconostoc citreum）TD1为供试菌，采用响应面法优化该菌株产胞外多糖（EPS）条件，并对其胞外多糖的 抗氧化性进行研究。 结果表明，菌株TD1产胞外多糖的最优条件为蔗糖109 g/L、Ca2+ 0.2 mmol/L、无水乙酸钠6.7 g/L。 在此优化条件 下，EPS含量为（57.58±2.04） g/L，是优化前（32.71 g/L）的1.76倍。分别测定上述发酵条件获得的粗EPS的抗氧化能力，结果表明，菌株 TD1所产的胞外多糖具有良好的体外抗氧化活性，随着浓度的增加清除能力亦增强，对超氧阴离子自由基、羟基自由基、DPPH自由 基和NO2清除率分别为（55.23±2.18）%、（95.34±2.33）%、（56.61±3.09）%和（5.32±0.18）%。

Optimization of conditions of exopolysaccharide production from Leuconostoc citreum TD1 by response surface methodology and its antioxidant activityYE Guangbin

Using Leuconostoc citreum TD1 as the tested strain, the conditions of exopolysaccharide (EPS) productionby L. citreum TD1 were optimized by response surface methodology, and the in vitro antioxidant activity of EPS was studied. The results showed that the optimal conditions of EPS pro- duction by L. citreum TD1 were determined as follows: sucrose 109 g/L, Ca2+ 0.2 mmol/L and anhydrous sodium acetate 6.7 g/L. Under the optimal conditions, the production of EPS was (57.58±2.04) g/L, which was 1.76 times that of before optimization (32.71 g/L). Determination results of in vitro antioxidant activity of crude EPS under the optimal conditions showed that the EPS by L. citreum TD1 had good in vitro antioxidant activity, and the scavenging ability increased with the increase of EPS content. The scavenging rates of superoxide anion radical, hydroxyl radical, DPPH free radi- cals and NO2 were (55.23±2.18)%, (95.34±2.33)%, (56.61±3.09)% and (5.32±0.18)%, respectively.