Abstract Chemical sanitizers are commonly used for fresh produce washing to reduce potential presence of foodborne pathogens and spoilage bacteria, and to prevent cross-contamination. In this study, we evaluated the susceptibility of foodborne pathogens, including Shiga-toxigenic Escherichia coli, Salmonella enterica, and Listeria monocytogenes, to free chlorine (FC) and peracetic acid (PAA) in spinach and romaine lettuce rinsates as simulated leafy green wash water. All inoculated pathogens exhibited notably enhanced tolerance (over 2 log of increased recovery) to FC, but not to PAA, when treated in fresh produce rinsates in comparison to that in sterile water. Both FC and PAA effectively inactivated the inoculated foodborne pathogens, rendering them undetectable after 30 s exposure to 10 mg/L FC or 30 mg/L PAA, by selective plating or non-selective enrichment. However, potentially viable cells for all the inoculated foodborne pathogens were detected by PMA-qPCR, especially in wash water samples treated with PAA at concentrations up to 50 mg/L. While laser confocal microscopy after differential staining suggested significant presence of viable but non-culturable (VBNC) populations in PAA treated wash water samples, resuscitation in vitro of the potential VBNC cells was not achieved. This study provides scientific data to better understand the risks of potential VBNC foodborne pathogens during fresh produce washing.

中文翻译：

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食源性病原体对生产冲洗水中的消毒剂的易感性和可能诱导有活力但不可培养的状态

摘要 化学消毒剂通常用于清洗新鲜农产品，以减少食源性病原体和腐败细菌的潜在存在，并防止交叉污染。在这项研究中，我们评估了食源性病原体（包括产志贺毒素大肠杆菌、肠沙门氏菌和单核细胞增生李斯特氏菌）对菠菜和长叶莴苣冲洗液中游离氯 (FC) 和过氧乙酸 (PAA) 的敏感性作为模拟绿叶清洗水. 与无菌水相比，在新鲜农产品冲洗液中处理时，所有接种的病原体对 FC 表现出显着增强的耐受性（恢复增加超过 2 个对数），但对 PAA 则没有。FC 和 PAA 均可有效灭活接种的食源性病原体，使其在暴露于 10 mg/L FC 或 30 mg/L PAA 30 秒后检测不到，通过选择性电镀或非选择性富集。然而，通过 PMA-qPCR 检测到所有接种的食源性病原体的潜在活细胞，特别是在用浓度高达 50 mg/L 的 PAA 处理的洗涤水样品中。虽然差异染色后的激光共聚焦显微镜表明在 PAA 处理的洗涤水样品中显着存在可行但不可培养的 (VBNC) 群体，但未实现潜在 VBNC 细胞的体外复苏。这项研究提供了科学数据，以更好地了解新鲜农产品洗涤过程中潜在的 VBNC 食源性病原体的风险。虽然差异染色后的激光共聚焦显微镜表明在 PAA 处理的洗涤水样品中显着存在可行但不可培养的 (VBNC) 群体，但未实现潜在 VBNC 细胞的体外复苏。这项研究提供了科学数据，以更好地了解新鲜农产品洗涤过程中潜在的 VBNC 食源性病原体的风险。虽然差异染色后的激光共聚焦显微镜表明在 PAA 处理的洗涤水样品中显着存在可行但不可培养的 (VBNC) 群体，但未实现潜在 VBNC 细胞的体外复苏。这项研究提供了科学数据，以更好地了解新鲜农产品洗涤过程中潜在的 VBNC 食源性病原体的风险。