Zhao Qian, Zhao Qingling, Li Jiabo, Yi Lanhua
College of Food Science, Southwest University, Chongqing 400715, China.
Research Center for Fruits and Vegetables Logistics Preservation and Nutritional Quality Control, Southwest University, Chongqing 400715, China.
Foods. 2024 May 8;13(10):1448. doi: 10.3390/foods13101448.
Fresh-cut vegetables are widely consumed, but there is no food preservative available to selectively inhibit vancomycin-resistant , 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 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 . 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 in fresh-cut lettuce showed that 99.97% of vancomycin-resistant 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 . Simultaneously, it exhibited membrane depolarization after analysis using DiSC(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.
鲜切蔬菜被广泛食用，但目前尚无可用的食品防腐剂能选择性抑制耐万古霉素菌，而耐万古霉素菌在鲜切蔬菜中是严重的健康威胁。为开发一种有前景的食品生物防腐剂，合成了一种细菌素——副菌素wx7，它对耐万古霉素菌表现出选择性抑制作用，最低抑菌浓度（MIC）值为4 - 8μM。在高浓度下，它在1小时内呈现即时杀菌模式，并伴随对耐万古霉素菌的细胞裂解。通过碘化丙啶/ SYTO9染色观察，其致死效应呈剂量依赖性显现。在鲜切生菜上对耐万古霉素菌进行的体内对照实验结果表明，用64μM副菌素wx7处理7天后，99.97%的耐万古霉素菌死亡，且不影响总细菌数。此外，还研究了副菌素wx7的作用机制。共聚焦显微镜显示副菌素wx7既位于细胞膜上，也存在于细胞质中。对于细胞膜，使用SYTOX Green染色和DNA泄漏对膜通透性的研究表明，副菌素wx7破坏了耐万古霉素菌的膜完整性。同时，使用DiSC(5)分析后发现它表现出膜去极化。通过扫描电子显微镜观察到，细胞膜的损伤导致细胞变形。当副菌素wx7进入细胞质后，会诱导内源性活性氧的产生。
