乳酸明串珠菌(Leuconostoc lactis)L2体内耐受性及产胞外多糖条件研究

The in vivo tolerance of Leuconostoc lactis L2 and its condition study on exopolysaccharide production

通过对乳酸明串珠菌(Leuconostoc lactis,Leu.lactis)L2进行耐pH、耐胆盐、耐NaCl能力的测定,评价其体内益生特性。结果表明,该菌株具有较强耐酸、耐胆盐及耐NaCl能力,是具有益生潜力的优良菌株。为提高Leu.lactis L2胞外多糖(Exopolysaccharide, EPS)的产量,结合单因素试验,对该菌株产EPS的培养基组分和发酵条件进行优化。优化后的条件为:蔗糖80 g·L^-1、蛋白胨10 g·L^-1、酵母提取物15 g·L^-1、乙酸钠3 g·L^-1、柠檬酸铵3 g·L^-1、磷酸氢二钾6 g·L^-1、吐温80 3 mL·L^-1、初始pH值6.5、摇床转速120 r·min^-1、培养温度30°C时,Leu.lactis L2 EPS产量达到18.31 g·L^-1,比优化前提高了2.36倍,为乳酸菌EPS的规模化生产提供理论依据。

In this study,the in vivo tolerance of Leuconostoc lactis(Leu.lactis)L2 was evaluated by the determination of pH tolerance,bile salt tolerance and NaCl tolerance.The results showed that the strain had strong acid resistance,bile salt resistance and NaCl resistance,and was an excellent strain with probiotic potential.In order to increase the yield of Leu.lactis L2 exopolysaccharide(EPS),the medium component and fermentation condition were optimized by single factor experiment.The optimized EPS production conditions were as follows:sucrose 80 g·L-1,peptone 10 g·L-1,yeast extract 15 g·L-1,sodium acetate 3 g·L-1,ammonium citrate 3 g·L-1,dipotassium hydrogen phosphate 6 g·L-1,Twain 803 mL·L-1,initial pH value 6.5,shake speed 120 r·min-1,culture temperature 30°C.The yield of Leu.lactis L2 EPS reached 18.31 g·L-1,which was 2.36 times higher than that before optimization.It provided a theoretical basis for the large-scale production of lactic acid bacteria EPS.