Integrative omics analysis of ohmic heating-induced sublethal injury and repair in Staphylococcus aureus

Ohmic heating presents safety concerns in food industry due to the presence of sublethally injured cells. However, the molecular mechanisms underlying OH-induced injury and subsequent repair remain poorly understood. To address this, this study employed Astral data-independent acquisition (DIA) proteomics, non-targeted metabolomics, and validation of transcriptional level validation to comprehensively analyze the formation and repair mechanisms of Staphylococcus aureus (S. aureus) cells. The result revealed that the morphology was damaged by ohmic heating treatment while restored after repair. Additionally, there were 428 differentially expressed proteins (DEPs) (90 upregulated and 330 downregulated) and 426 differentially expressed metabolites (DMs) (168 upregulated and 258 downregulated) following injury. In contrast, the bacteria that had repaired to an end-repair state (sublethal rate near zero and bacterial population growth rates plateaued) exhibited 258 DEPs (51 upregulated and 201 downregulated) and 362 DMs (194 upregulated and 168 downregulated) compared to unrepaired S. aureus cells. Notably, metabolic pathways enriched during injury and repair were distinct, and changes in cell structure-related DEPs and DMs demonstrated that disrupted membrane integrity and osmotic balance, while compensatory upregulation of energy metabolism pathways reflected cellular adaptation to sublethal stress. There was also a noted impairment in transcriptional functions, antioxidant capacity, and virulence factors after ohmic heating treatment. Although the bacteria exhibited basic physiological characteristics after repairing to terminal-repair phase, the sublethal injury resulted in DEPs and DMs that were difficult to restore to baseline levels. Our study provides new insights into the sublethal damage and repair mechanisms of ohmic heating-treated S. aureus, informing the development of optimized ohmic heating protocols to mitigate resuscitation risks in food processing applications.