双歧杆菌BB12胞外多糖发酵条件优化及抗氧化活性研究

Optimization of fermentation conditions and antioxidant activities of exopolysaccharide from Bifidobacterium lactis Bb12

为提高双歧杆菌BB12胞外多糖(exopolysaccharide,EPS)的产量,并探究其抗氧化活性,该文通过单因素试验分析初始p H值、培养温度和培养时间对胞外多糖产量的影响,在此基础上通过响应面法进一步优化发酵工艺参数,并对胞外多糖的还原能力、·OH和·O2-的清除作用进行了研究。结果表明,最优发酵条件修正后为:初始p H值8、培养温度37℃、培养时间101 h。在此条件下进行发酵验证,得到的胞外多糖产量为(131.6±0.82)mg/L。体外抗氧化性试验表明双歧杆菌胞外多糖具有还原能力,对·OH和·O2-的50%清除浓度(IC50)均低于抗坏血酸(Vc)。为双歧杆菌胞外多糖的大规模生产及抗氧化机制的研究提供了可靠的理论依据。

The purpose of this study was to enhance exopolysaccharide(EPS)yield from Bifidobacterium lactis BB12(BB12)and to determine the antioxidant activity of EPS.Single factor experiment was used to analyze the effects of initial pH,temperature and time on the yield of EPS.Subsequently,the fermentation parameters were further improved using response surface methodology.The antioxidant activity was determined by ferric reducing power of EPS,and the-OH and-O2 scavenging rate.The results showed that initial p H of 8,temperature of 37℃,and incubation time of 101 h was the optimum processing condition for producing EPS.Finally,the yield of EPS reached 131.6±0.82 mg/L.In addition,the reducing ability of EPS was further evaluated using in vitro antioxidant test,which IC50-OH and-O2 was lower than that of Vc.Our research provided a reliable theoretical basis for the EPS commercial scale production using BB12,as well as foundations of understanding for antioxidant mechanism.