儿茶素对EHEC O157:H7的抑制作用及其机理研究

发布时间：2018-06-01 22:56

  本文选题：儿茶素 + EHEC　； 参考：《湖南农业大学》2014年硕士论文

【摘要】：EHEC O157:H7是通过污染食品导致疫情暴发的一种常见病原微生物,且临床上难以治疗。儿茶素是茶叶中多酚类物质的主体成分,早在神农时期,茶就被发现能被用于杀菌消炎,其主要功能物质即为茶多酚。茶多酚作为功能性抑菌成分已有大量研究与少量实际应用。但其对EHEC O157:H7的影响却少见报道,因此本试验主要是系统研究儿茶素对EHEC O157:H7的影响,通过活菌计数、双向电泳等方法,考察了不同环境因素对儿茶素抑制EHEC O157:H7生长的影响,模拟的人体消化道环境中儿茶素对EHEC O157:H7的杀菌作用,以及经儿茶素处理前后EHEC O157:H7总蛋白的变化,结果显示： 1、环境因素对儿茶素抑制EHEC O157:H7生长的影响儿茶素对EHEC O157: H7最小抑菌浓度为1.25g/L；儿茶素对该菌株的抑制作用具有良好的稳定性,在37℃的pH中性环境中,抑制作用较明显；同时,NaCl与儿茶素能起到协同抑菌作用。 2、模拟人体消化道环境中儿茶素对EHEC O157:H7的杀菌作用儿茶素对EHEC O157:H7的最小杀菌浓度为5g/L；EHEC O157:H7的生长并不适应胃液环境,活菌数与培养时间及儿茶素的浓度均呈负相关；在人工肠液中随培养时间增长,儿茶素的杀菌作用越明显,儿茶素浓度越高,活菌数越少,最小杀菌浓度为10g/L；胆盐的存在对EHEC O157:H7的生长有一定的抑制,儿茶素的加入与胆盐有协同作用产生,在胆盐环境中,儿茶素的最小杀菌浓度为10g/L。 3、儿茶素处理前后EHEC O157:H7总蛋白的变化采用蛋白质双向电泳技术对儿茶素引起的细菌蛋白质变化情况进行分析,分别设置正常组A和试验组B。用Image Master TM2D Platinum (Version7.0)对图谱进行分析得出：差值在3倍及以上的蛋白表达差异点中,34个蛋白点发生了可重复的显著变化,2个蛋白点被上调,12个蛋白点被下调,未表达的蛋白有20个,未产生新的蛋白表达。这说明了儿茶素对EHEC O157:H7蛋白的影响主要还是表现在对蛋白质表达的下调和抑制某些蛋白质的表达,且儿茶素的抑制作用不会产生新的蛋白质表达。
[Abstract]:EHEC O157:H7 is a common pathogenic microorganism caused by contaminated food and is difficult to be treated clinically. Catechin is the main component of polyphenols in tea. As early as Shennong period, tea has been found to be used in sterilization and anti-inflammatory, its main functional substance is tea polyphenols. Tea polyphenols as a functional bacteriostatic component has been a lot of research and a small number of practical applications. However, the effects of catechins on EHEC O157:H7 were rarely reported. The effects of catechins on EHEC O157:H7 were studied systematically. The effects of different environmental factors on the inhibition of EHEC O157:H7 growth were investigated by means of living bacteria count and two-dimensional electrophoresis. The bactericidal effect of catechin on EHEC O157:H7 and the changes of total EHEC O157:H7 protein before and after catechin treatment in human digestive tract were simulated. The results showed that: 1. The effect of environmental factors on the inhibition of EHEC O157:H7 growth by catechin was studied. The minimal inhibitory concentration of catechin on EHEC O157: H7 was 1.25 g / L, and the inhibitory effect of catechin on EHEC O157: H7 was stable in pH neutral environment at 37 鈩，

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