We studied the viable but nonculturable (VBNC) state of the human pathogen Escherichia coli O157:H7 during desiccation using genomic, proteomic, and direct methods in a model soil under controlled conditions. During desiccation, the bacterial cells reduced their culturability, protein synthesis, and DNA replication, and changed their morphology. Four days after rewetting of dry soil, the culturability of E. coli recovered, and protein synthesis was restored. A total of 2,324 proteins were differently expressed in the VBNC state compared to the culturable state and identified. Morphological changes during the VBNC state paralleled the downregulation of cytoskeletal proteins and enzymes of the tricarboxylic acid cycle. On the contrary, proteins involved in nutrient transport, membrane, chemotactic, flagellar, virulence, and adhesion were upregulated. Overall, our results indicated that low soil moisture can induce the VBNC state in E. coli O157:H7 but this state can revert to culturability and full metabolic activity upon soil rewetting. These findings can be important aspects in assessing the environmental risks posed by microbial pathogens in soil.

中文翻译：

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人工土壤中低水分诱导的活但不可培养 (VBNC) 大肠杆菌 O157:H7 的蛋白质组学变化

我们在受控条件下使用基因组、蛋白质组学和直接方法在模型土壤中研究了干燥过程中人类病原体大肠杆菌 O157:H7 的可行但不可培养 (VBNC) 状态。在干燥过程中，细菌细胞的可培养性、蛋白质合成和 DNA 复制降低，并改变了它们的形态。干土再润湿四天后，大肠杆菌的可培养性恢复，蛋白质合成恢复。与可培养状态相比，共有 2,324 种蛋白质在 VBNC 状态下有不同的表达并被鉴定。VBNC 状态期间的形态变化与细胞骨架蛋白和三羧酸循环酶的下调平行。相反，参与营养运输、膜、趋化、鞭毛、毒力和粘附的蛋白质被上调。总体而言，我们的结果表明，低土壤湿度可以诱导大肠杆菌 O157:H7 中的 VBNC 状态，但这种状态可以在土壤再润湿后恢复到可培养性和完全代谢活动。这些发现可能是评估土壤中微生物病原体造成的环境风险的重要方面。