乳酸菌发酵生产胞外多糖条件优化研究

The Conditions Optimization of Lactobacillus Exopolysaccharides Fermentation

乳酸菌胞外多糖是由乳酸菌发酵产生,分泌在细胞外的多糖类化合物。它具有改变乳制品风味和流体特性的作用,能够提高免疫的应答灵敏性,而且还具有抗肿瘤的活性。试验从4株乳酸菌中经过发酵比较,筛选出一株EPS产量较高的乳酸菌。通过单因素与正交试验,对乳酸菌生产EPS培养基的组成和生长条件的影响进行优化,结果表明,乳酸乳球菌乳亚种LL9为合成EPS最高产品系,发酵生产胞外多糖最佳工艺条件为:发酵时间为24 h,接种量8.0%,发酵温度为37℃,培养基初始p H为7.0,选用乳糖作为碳源,用大豆蛋白胨作为氮源。根据优化的培养条件,EPS的产量可达到262.628 mg/L。

Lactobacillus exopolysaccharide produced by lactobacillus fermentation, the extracellular secretion is a kind of carbohydrates otten seep into the culture medium. Lactobacillus exopolysaccharide have the function of the flavor of dairy products and fluid properties changing, it also can enhance the immune response sensitivity and has the activity of antitumor. In this study, multiple strains ofLactococcus lactis subsp, lactis LL9 has be screened from four lactic acid bacteria in fermented comparison, a high yielded EPS lactic acid bacteria have been screened out. By Single factor and orthogonal experiment, the composition of medium and the growth conditions to the yield of EPS is probed. The experiment result shows that Lactococcus lactis subsp, lactis LL9 is the highest product strain. The result indicates that the output of the exopolysaccharide can reach to 262.628 mg/L under the conditions, ferment for 24 h, 8% inoculum, fermentation temperature 37 ℃, initial pH of medium 7.0 and selecting the lactose as carbon and soy peptone as nitrogen.