[关键词]
[摘要]
本文以传统发酵食品中筛选的39株乳酸菌为研究对象,采用牛津杯法筛选具有优良抑菌特性的乳酸菌,分别对菌株的生长曲线、产酸能力、耐胆盐、耐渗透压、耐酸碱、抑菌谱进行检测,并研究代谢产物的稳定性。结果表明:筛选出三株具有良好抑菌特性的菌株,分别为植物乳杆菌HS011、德氏乳杆菌HS023、嗜热链球菌HS033。三株菌经培养20 h后,发酵液pH分别由5.44、5.44、5.42下降到3.55、3.54、3.57;三株乳酸菌能耐受0.1%以下的胆盐和14%的NaCl溶液;在pH 5.0~8.0时生长情况良好;且具有较为广泛的抑菌谱,对大肠杆菌O157:H7、蜡样芽孢杆菌、单增李斯特氏菌、阪崎肠杆菌等均有较好抑制作用,但对霉菌和酵母无作用;代谢产物经温度(20~121 ℃)、pH(2.0~8.0)处理后仍有较好抑菌活性;经木瓜蛋白酶、胰蛋白酶、胃蛋白酶、蛋白酶K、过氧化氢酶处理后菌株代谢产物抑菌活性未有明显变化。表明从传统发酵食品中筛选的乳酸菌具有良好益生特性,其代谢产物稳定性好,可作为发酵产品中的生产菌株,可进一步开发利用。
[Key word]
[Abstract]
To identify lactic acid bacteria with excellent antibacterial properties, 39 strains of lactic acid bacteria from traditional fermented food products were screened using the Oxford cup method. The growth curve, acid production ability, bile salt tolerance, osmotic tolerance, acid and alkali tolerance, and antibacterial spectrum of each of the selected strains were investigated. Then, the stability of the metabolites of each of the chosen strains was studied. Finally, three strains with good antibacterial properties were identified. They are Lactobacillus plantarum HS011, Lactobacillus delbrueckii HS023, and Streptococcus thermophilus HS033. The pH values of their fermentation supernatants decreased from 5.44, 5.44 and 5.42 to 3.55, 3.54 and 3.57, respectively, after cultivation for 20 h. The three lactic acid bacteria can tolerate less than 0.1% bile salt and 14% NaCl, and grow well within the pH range of 5.0~8.0. All three strains have abroad bacteriostatic spectrum and can effectively suppress the growth of Escherichia coli O157:H7, Bacillus cereus, Listeria monocytogenes, and Enterobacter sakazakii. However, the chosen L. plantarum strains have no inhibitory effects on molds and yeasts. The metabolites of these strains retained their antibacterial activity even after various treatments such as temperature (20~121 ℃), pH (2.0~8.0), papain, trypsin, pepsin, proteinase K, and catalase treatments. The lactic acid bacteria isolated from traditional fermented food products have good probiotic properties, and their metabolites are stable, and can, therefore, be used as starters in fermented products and can be further developed and utilized.
[中图分类号]
[基金项目]
四川省科技计划项目(2019YJ0261;2020YFN0153);生物技术与资源利用教育部重点实验室开放课题(KF2020008);西南民族大学研究生创新项目(CX2020SZ43)