ABSTRACT

Bacteria may enter into a viable but nonculturable (VBNC) state as a response to stresses, such as those found in food processing. Cells in the VBNC state lose the ability to grow in a conventional culture medium but man recover culturability. The viability, culturability and intracellular reactive oxygen species (ROS) of Salmonella Enteritidis and Shigella flexneri were evaluated under stress conditions to induce a VBNC state. Cells were maintained under nutritional, osmotic and cold stresses (long-term induction) in Butterfield's phosphate solution plus 1.2 M of NaCl at 4°C and under nutritional and oxidative stresses (short-term induction) in 10 mM of H₂O₂. Culture media, recovery agents, sterilization methods of media and incubation temperature, were combined and applied to recover the culturability of the VBNC cells. Salmonella entered in the VBNC state after 135 days under long-term induction, while Shigella maintained culturability after 240 days. Under short-term induction, Salmonella and Shigella lose culturability after 135 and 240 min, respectively. Flow cytometric analysis revealed viable cells and intracellular ROS in both species in VBNC. It was not possible to recover the culturability of VBNC cells using the 42 combinations of different factors.

中文翻译：

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肠炎沙门氏菌和弗氏志贺氏菌在存活但不可培养状态的诱导和恢复过程中的行为

摘要

细菌可能会进入一种有活力但不可培养 (VBNC) 的状态作为对压力的反应，例如在食品加工中发现的压力。处于 VBNC 状态的细胞失去在常规培养基中生长的能力，但人类恢复了可培养性。的生存能力，培养性和细胞内活性氧类物质（ROS）的沙门氏菌肠炎和痢疾杆菌中应力的条件下评价以诱导VBNC状态。细胞在 4°C 的 Butterfield 磷酸盐溶液加 1.2 M NaCl 中的营养、渗透和冷应激（长期诱导）下以及在 10 mM H ₂ O _{2 中的}营养和氧化应激（短期诱导）下维持. 将培养基、恢复剂、培养基的灭菌方法和孵育温度组合起来并应用以恢复VBNC细胞的可培养性。沙门氏菌在长期诱导 135 天后进入 VBNC 状态，而志贺氏菌在 240 天后保持可培养性。在短期诱导下，沙门氏菌和志贺氏菌分别在 135 和 240 分钟后失去可培养性。流式细胞术分析揭示了 VBNC 中两个物种的活细胞和细胞内 ROS。使用 42 种不同因子的组合无法恢复 VBNC 细胞的可培养性。