该研究从哈尔滨周边地区农户家的自然发酵面团中分离纯化乳酸菌，分别评价分离菌株的耐酸耐胆盐及抑菌特性，并利用溶血性试验和抗生素敏感试验评估其安全性。以邻苯二甲醛法对乳酸菌菌株的降胆固醇能力进行体外分析，并利用高脂模型小鼠研究其体内降胆固醇功能。结果共分离得到16株乳酸菌，其中发酵乳杆菌FD-8在酸性和胆盐条件下存活率可达80.21%和75.98%，对致病性大肠杆菌、金黄色葡萄球菌和鼠伤寒沙门氏菌均有一定的抑菌作用且安全性良好。FD-8菌株的体外降解胆固醇率达到85.66%，体内饲喂FD-8菌株5 w后能明显降低高脂饮食小鼠的体质量和肝脏指数，改善高脂饮食诱导的小鼠血清及肝脏中总胆固醇、低密度脂蛋白胆固醇和甘油三酯水平的改变，达到降血脂的目的。该研究从自然发酵面团中分离到的发酵乳杆菌FD-8具备良好的耐酸、耐胆盐和抑菌特性，能够在体内外发挥降胆固醇作用，同时无溶血性且对某些抗生素表现一定的敏感性，对于进一步开发降胆固醇产品具有重要意义。

Lactic acid bacteria (LAB) were isolated and purified from naturally fermented dough obtained from farmers in the areas surrounding Harbin. The tolerance capacities of LAB were evaluated under acidic pH and bile salt conditions. The antimicrobial capacities of the isolated strains were evaluated using a bacteriostatic test, and the safety of LAB was evaluated using hemolytic and antibiotic sensitivity tests. The cholesterol-lowering ability of the isolates was further analyzed using the ortho-phthalaldehyde method in vitro, and the cholesterol-lowering function was studied using a high-fat diet mouse model. The results showed that a total of 16 LAB strains were isolated, among which the survival rate of Lactobacillus fermentum FD-8 was 80.21% and 75.98% under acidic and bile salt conditions, respectively. FD-8 had certain bacteriostatic activity and good safety against pathogenic Escherichia coli, Staphylococcus aureus, and Salmonella typhimurium. The cholesterol degradation rate of FD-8 reached 85.66% in vitro. FD-8 intervention in the high-fat diet mouse model showed that after feeding FD-8 for 5 weeks in vivo, this strain could significantly reduce the body weight and liver indexes to alleviate obesity in the mice. FD-8 also significantly regulated the variations induced by the high-fat diet in TC, TG, and LDL levels in the serum and liver of the mice, and thus achieved the goal of reducing blood lipid levels. To summarize, the results indicated that L. fermentum FD-8 isolated from naturally fermented dough has good tolerance to acid and bile salts as well as good antibacterial property, and can play a role in cholesterol-lowering in vitro and in vivo, which is of great significance for the development of cholesterol-lowering products in the future.

黑龙江省省属高等学校基本科研业务费科研项目（2020KYYWF-FC04）；哈尔滨体育学院科研实验室（平台）专项项目（LAB2021-10）