北疆传统发酵生奶酪中乳酸菌的耐受性及益生特性测定

Tolerance and probiotic characteristics of lactic acid bacteria in traditional fermented raw cheese in northern Xinjiang

摘要:

【背景】北疆乳制品中生奶酪作为发酵乳制品，其中有多种微生物的参与，是优质食品级微生物的宝贵来源，然而其中蕴含的丰富的微生物资源也面临着流失。【目的】研究已筛选出的41株乳酸菌的生长曲线变化规律，并对其在低pH环境的耐酸特性及益生特性进行分析。【方法】通过人工模拟胃肠液和含0.3%、0.5%、1.0%浓度牛胆盐溶液培养，对从生奶酪中分离鉴定的41株乳酸菌菌株进行人工胃肠液、牛胆盐耐受性试验。【结果】41株乳酸菌中有6株乳酸菌(编号为QM-5、QM-27、UM-12、UM-18、NM-11和NM-14)均能在pH值分别为2.0、2.5、3.0、3.5、4.0时生长较好，在pH 2.0的环境下也保持一定程度的生长。菌株存活率大于50%，乳酸菌含量为10⁸ CFU/mL以上。从生奶酪分离的乳酸菌有极强的耐酸、耐胆盐特性，可以预测在胃肠道环境生存。41株菌对大肠杆菌(Escherichia coli)、金黄色葡萄球菌(Staphylococcus aureus)和枯草芽孢杆菌(Bacillus subtilis)均有抑制作用。【结论】通过比较耐酸性、胃肠道模拟、胆盐耐受性和抑菌特性等实验结果，初步选出了3株综合耐受性良好的优势菌株。

Abstract:

[Background] Among dairy productsin northern Xinjiang, raw cheese harbors a variety of microorganisms and is a valuable source of high-quality food-grade microorganisms. However, the rich microbial resources contained therein are facing the risk of being lost. [Objective] To establish the growth curves of 41 strains of lactic acid bacteria isolated from raw cheese and characterize their tolerance to low pH environment and probiotic characteristics. [Methods] Forty-one strains of lactic acid bacteria isolated from raw cheese were cultured with simulated gastric fluid and the media containing 0.3%, 0.5%, and 1.0% bovine bile salt. [Results] Among the 41 strains of lactic acid bacteria, 6 strains (QM-5, QM-27, UM-12, UM-18, NM-11, and NM-14) grew well at pH 2.0, 2.5, 3.0, 3.5, and 4.0. In the medium at pH 2.0, QM-5 strain maintained a survival rate above 50% and the viable count more than 10⁸ CFU/mL. The lactic acid bacteria isolated from raw cheese has strong resistance to acid and bile salt and can survive in the gastrointestinal environment. Furthermore, the 41 strains had inhibitory effects on Escherichia coli, Staphylococcus aureus, and Bacillus subtilis. [Conclusion] Three dominant strains with antibacterial activity and comprehensive tolerance to acid, simulated gastric fluid, and bile salt were screened out.