新疆酸马奶中高产胞外多糖乳酸菌筛选鉴定及培养条件优化研究

摘要

[ Objective ] A lactic acid bacteria with high EPS - producing capacity was screened from koumiss in Ili, Xinjiang, and the culture conditions of the lactobacillus was optimized in order to gain more EPS and provide theoretical basis for the culture conditions of lactobacillus with EPS - producing capacity. [ Method ] Production of EPS was measured by Phenol - H2SO4 method. This lactic acid bacteria with high EPS -producing capacity was identified by physiological biochemical characters and sugar fermentation tests. In order to study the effect of single factor on the EPS biosynthesis capacity, optimization of carbon and nitrogen source in medium and culture conditions such as time, pH for the lactic acid bacteria were carried out in the paper. [ Conclusion ] The results showed that this lactic acid bacteria was identified as Lactobacillus casei. Glucose(2% )and peptone(1.5% )was favorable carbon and nitrogen source for this lactobacillus casei to pro-duce EPS. The optimal culture conditions for producing EPS were: fermented for 28 h, initial pH 6.5. The maximum biosynthesis amount of EPS was 121.6 mg/L.%[目的]从新疆伊犁牧民自制酸马奶中筛选出一株高产胞外多糖的乳酸菌,并对该菌产胞外多糖的培养条件进行优化,从而得到更多的胞外多糖,为乳酸菌产胞外多糖的培养条件提供理论依据.[方法]应用苯酚硫酸法筛选出产胞外多糖量高的乳酸菌,通过生理生化和糖发酵实验对产糖量高的乳酸菌进行鉴定；在培养条件的优化试验中,采用单次单因子法,探索初始pH值、培养时间、碳源及氮源等对乳酸菌产胞外多糖量的影响.[结论]鉴定出产胞外多糖量高的乳酸菌为干酪乳杆菌,并且确定干酪乳杆菌产胞外多糖的最佳合成条件为葡萄糖2％,蛋白胨1.5％,发酵时间28 h,初始pH值6.5,此条件下所合成胞外多糖量为121.6 mg/L.