PDF(Pubmed)
Abstract：
Fresh-cut vegetables are widely consumed, but there is no food preservative available to selectively inhibit vancomycin-resistant E. faecalis, which is a serious health menace in fresh-cut vegetables. To develop a promising food biopreservative, a bacteriocin, paracin wx7, was synthesized, showing selective inhibition against E. faecalis with MIC values of 4-8 μM. It showed instant bactericidal mode within 1 h at high concentrations with concomitant cell lysis against vancomycin-resistant E. faecalis. Its lethal effect was visualized in a dose-dependent manner by PI/SYTO9 staining observation. The results of an in vivo control experiment carried out on E. faecalis in fresh-cut lettuce showed that 99.97% of vancomycin-resistant E. faecalis were dead after 64 μM paracin wx7 treatment for 7 days without influencing total bacteria. Further, the action mechanism of paracin wx7 was investigated. Confocal microscopy showed that paracin wx7 was located both on the cell envelope and in cytoplasm. For the cell envelope, the studies of membrane permeability using SYTOX Green dyeing and DNA leakage revealed that paracin wx7 damaged the membrane integrity of E. faecalis. Simultaneously, it exhibited membrane depolarization after analysis using DiSC3(5). Damage to the cell envelope resulted in cell deformation observed by scanning electron microscopy. On entering the cytoplasm, the paracin wx7 induced the production of endogenous reactive oxygen species.
摘要：
鲜切蔬菜被广泛食用，但是没有食品防腐剂可以选择性抑制耐万古霉素的粪肠球菌，这是一个严重的健康威胁鲜切蔬菜。为了开发一种有前途的食品生物防腐剂，细菌素,paracinwx7，合成，显示对粪肠球菌的选择性抑制,MIC值为4-8μM。它在高浓度下在1小时内显示出即时杀菌模式，并伴随着对万古霉素抗性粪肠球菌的细胞裂解。通过PI/SYTO9染色观察以剂量依赖性方式观察其致死作用。对鲜切生菜粪肠球菌进行的体内对照实验结果表明，在64μMparacinwx7处理7天后，99.97％的耐万古霉素粪肠球菌死亡，而不影响细菌总数。Further,研究了paracinwx7的作用机理。共聚焦显微镜显示paracinwx7位于细胞包膜和细胞质中。对于单元格信封，SYTOXGreen染色和DNA渗漏对细胞膜通透性的研究表明，paracinwx7破坏了粪肠球菌的膜完整性。同时,使用DiSC3（5）分析后显示膜去极化。通过扫描电子显微镜观察到细胞包膜的损伤导致细胞变形。一旦进入细胞质，paracinwx7诱导内源性活性氧的产生。
