泡菜、传统腊肠中降胆固醇乳酸菌的筛选及鉴定

摘要

[Objective] To obtain cholesterol-reducing lactic acid bacteria (tAB), we isolated and identified strains of LAB from indigenously fermented pickles and dried-sausage.[Methods] We screened original LAB strains based on the Calcium Carbonate-MRS medium (Calcium Carbonate-Man Rogosa and Sharp Medium) from pickles and sausage. The cholesterolreducing strains were confirmed by screening with in vitro cholesterol levels. These strains were identified by methods of morphologic observation, catalase reaction, carbohydrate reaction and 16SrRNA sequencing. [Results] We obtained two strains of LAB (LpT1 and LpT2), which presented a comparatively high ability of cholesterol reducing. The two strains also showed high acid resistance and bile salt tolerance. The time of LpT1 entering the logarithm phase of growth and stationary phase of growth was 14 hours and 22 hours after cultivated, while that of LpT2 was 12 hours and 20 hours after cultivated. These two strains survived for at least 4 hours in the MRS broth with pH 2.0 and grew well in the MRS broth containing 0.2％ bile salt, and we identified these two strains to be Lactobacillus plantarum by 16SrRNA sequencing. [Conclusion] The two LAB strains could reduce cholesterol in vitro and resist acid and bile salt.%[目的]筛选具有降胆固醇功能的乳酸菌菌株,为乳酸菌体外、体内的降胆固醇生理特性和机理研究奠定基础.[方法]以碳酸钙-MRS选择性培养基(Calcium Carbonate-Man Rogosa and Sharp Medium)从中国传统食品泡菜、腊肠中筛选乳酸菌,应用改良的胆固醇筛选培养基筛选具有较高降胆固醇能力的乳酸菌菌株,并研究其耐酸性,耐胆盐活性,生长曲线及产酸特性;结合菌落形态学、接触酶反应、革兰氏染色、碳水化合物微量鉴定管及16SrRNA寡核苷酸碱基序列分析鉴定菌株.[结果]筛选得到的两个菌株LpT1和LpT2胆固醇降解率分别达到49.11%和50.03%,且呈现了较好的耐酸性和耐胆盐活性,其中LpT1在第14小时开始进入对数生长期,在第22小时进入生长稳定期,LpT2在第12小时进入对数生长曲线,第20小时进入稳定期;它们都能在pH2.0的MRS培养基中存活至少4 h,在含0.2%胆盐的MRS培养基中生长良好,经鉴定均为植物乳杆菌.[结论]筛选得到的植物乳杆菌具有较高的胆固醇降解率,同时表现了较强的耐酸、耐胆盐活性,具有重要的生产应用价值,为后续的体内活性、机理研究提供了原始菌株并奠定了良好的基础.