Multi-omics insight into the role of PagC facilitating the VBNC state formation of Salmonella Typhimurium under plasma-activated water (PAW) stress.

Plasma-activated water (PAW) is a promising technology for food disinfection with high efficiency and sustainability. However, there is a risk that PAW can induce the viable but non-culturable (VBNC) state in pathogens such as Salmonella, which brings a challenge to the practical application of PAW. This study suggests that the outer membrane protein PagC plays a critical role in the VBNC state formation in Salmonella Typhimurium under PAW stress. Flow cytometry analysis revealed that the proportion of VBNC cells in the pagC deletion mutant (ΔpagC) was 77.6%, lower than that in the wild type (WT) of 85.2% after PAW treatment (ORP > 800 mV, pH < 2.3) for 12 min. ΔpagC exhibited severe damage in cell membrane integrity, suggesting the potential function of PagC in enhancing cell membrane integrity. The absence of pagC also resulted in an exacerbated depletion of intracellular ATP (dropping to 49.4% of WT) and a significant surge in ROS accumulation (increasing to 1.52-fold of WT). Transcriptomic and proteomic analyses revealed the disruption of energy metabolism, oxidative stress response and arginine biosynthesis in ΔpagC compared with WT. We propose a potential mechanism that PagC preserves membrane integrity to maintain membrane-associated energy metabolism, compensating for energy depletion caused by PAW, which supports the oxidative stress response and allows Salmonella Typhimurium to survive in the VBNC state. This study addresses the gap between the function of PagC and the VBNC state induced by PAW, and provides a theoretical basis for improving risk assessment of PAW technology.