冷水鱼肠道抑菌活性乳酸菌的筛选及其生理特性分析
Screening of lactic acid bacteria with inhibitory activity isolated from intestinal of cold water fish and analysis of its physiological property
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摘要: 利用牛津杯法对分离自冷水鱼肠道的24株乳酸菌进行筛选,得到具有明显抑菌活性的乳酸菌9株,基于菌株的16S rDNA基因序列进行系统发育分析,6株属于Lactococcus属,3株属于Enterococcus属。对9株乳酸菌发酵上清液进行抑菌成分分析和蛋白质性质实验,结果表明,9株乳酸菌的发酵上清液经排除酸和过氧化氢干扰后,对李斯特菌仍具有不同程度的抑制作用;有机酸的产生对实验菌株MHY3-2和MD-2抑菌活性的干扰影响较大,而菌株MB2-1和MD-1受有机酸干扰影响较小,且经排除酸和过氧化氢后的乳酸菌对李斯特菌的抑菌效果最为显著;分析发酵上清液中抑菌物质的蛋白质性质,发现除菌株MB2-2和MD-1对胰蛋白酶表现不敏感外,其余实验菌株发酵上清液经胃蛋白酶和胰蛋白酶处理后均失去抑菌活性,结果表明,实验菌株的发酵上清液中的抑菌物质具有蛋白质的性质,抑菌组分中可能存在类细菌素或细菌素组分。此外,对9株乳酸菌的抗生素耐药性进行初步分析,结果显示,所有实验菌株对氨苄西林、万古霉素、红霉素、氯霉素、环丙沙星和诺氟沙星均表现敏感,为冷水鱼肠道乳酸菌资源的开发利用奠定基础。Abstract: 9 strains of lactic acid bacteria with inhibitory activity were screened from 24 lactic acid bacteria isolated from cold water fish intestinal by using oxford cup method. 6 strains belonged to Lacterococcus genus and 3 strains belonged to Enterococcus genus by phylogenic analysis based on their partial 16S rDNA gene sequences. Cell-free fermenting supematants (CFSs) from 9 strains were performed to determine the inhibitory compounds and the proteninaceous nature of inhibitors. The result showed that CFSs of 9 lactic acid bacteria still exhibit different degree of inhibitory activity against Listeria monocytogenes after eliminating the effect of organic acid and hydrogen peroxide;the inhibitory activity of strains MHY3-2 and MD-2 were strongly dependent on the organic acid, whereas the influence of organic acid produced by strains MB2-1 and MD-1on the inhibitory activity were negligible. CFSs of strains MB2-1 and MD-1 after eliminating organic acid and hydrogen peroxide show significant antibacterial activity against Listeria monocytogenes among 9 strains. The activity of all tested strains was lost by treating with pepsin and trysin but strains MB2-2 and MD-1 not sensitive to trypsin. The results demonstrated that the inhibitory compound was proteinaceous in nature and likely is bacterion-like or bacterion. In addition, antibiotic resistance of 9 strains of lactic acid bacteria was preliminarily tested. 9 strains were sensitive to ampicillin, vancomycin, erythromycin, chloramphenicol, ciprofloxacin and norfloxacin. The safety aspects of strains with inhibitory activity studied could provid basis for exploitarion and application of lactic acid bacteria isolated from the intestine of cold water fish.