Inhibitory Effect Of Catechin On EHEC O157:H7and Mechanism Research

EHEC O157:H7is a common pathogenic microorganism leading to the outbreak through contaminating food, that is difficult to cure. As early as7,000years ago in primitive times, tea was found to be for antiseptic antiphlogistic. And catechin is a main polyphenol in tea. In order to provide more basis to prevent and control EHEC O157: H7, and study the effect of catechin on EHEC0157:H7deeply, this experiment studied the different environmental factors on the process of catechin inhibition of EHEC O157: H7growth, through method of living bacteria counting, dielectrophoresis etc. At the same time, human digestive would be stimulated to test the sterilization effect that catechin on EHEC O157:H7. And the data change of total protein, before and after catechin effecting on EHEC O157:H7, was also recorded. The results are as follows.1. Influence of environmental factor on catechin suppressing EHEC O157growth There is a stable inhibition of catechin to EHEC O157:H7. Especially, in neutral environment at37℃, the inhibition to EHEC O157:H7is significantly different to others environment. Furthermore, NaCl plays a good synergy effects to catechins’ inhibition.2. Sterilization of catechin to EHEC O157: H7in stimulated human digestive The Minimum Bactericidal Concentration of catechin was5g L-1for EHEC O157:H7. The growth of EHEC O157:H7did not adapt to the gastric environment, its viable counts and culture time were negatively correlated with catechin concentrations. The Bactericidal effect of catechin was increased significantly with the increase of culture time in artificial intestinal juice. Furthermore, the higher the catechin concentration is, the smaller the viable counts is. And the catechin minimum bactericidal concentration is10g L-1. Salts suppress the growth of EHEC O157:H7. And the participation of catechin lead to a good synergistic effect with salt inhibition effects. Viable counts of EHEC O157:H7decreased with the increase of the catechin and salt. And in this environment, the catechin minimum bactericidal concentration is10gL-1. 3. Total protein changes before or after catechin added into EHEC O157:H7broth Two-dimensional electrophoresis was used to analyze the bacterial protein changes caused by catechin addition. The normal group and experimental group were set with2.5g L-1catechin or none. Analyzing the map with Image Master TM2D Platinum (Version7.0), we find, in the value of3times or more protein expression differences, there were34protein points having taken place significant repeatable changes.2protein points were raised, and12protein points were decline. But20proteins had no expression, and there was no new protein expressed. All in all, the influence of catechin on EHEC O157:H7mainly performed in the aspects of wakening the protein express and suppress some protein expression. Under the adding of catehin, there would be no new protein expressed.