The deletion of the uvrY in Aeromonas veronii disrupted the BarA/UvrY two-component system, decreasing persister formation and bacterial resistance to multiple antibiotics.

Antibiotic resistance (AR) is increasingly recognized as a critical global public health threat. Aeromonas species, widely distributed in aquatic environments, have emerged as potential foodborne pathogens. These bacteria are frequently detected in water sources and various ready-to-eat foods, posing a significant risk to food safety and human health. Two-component systems (TCSs) are key regulators of stress tolerance and adaptive behaviors, but the role of the BarA-UvrY TCS in AR is unclear. In our study, multidrug-resistant Aeromonas veronii (A. veronii) strains isolated from the grass carp intestinal contents were used to investigate the role of uvrY in AR, and mutant strain (Δ uvrY) was constructed using homologous recombination. The growth characteristics of wild-type (WT), Δ uvrY, and complemented strains (C-Δ uvrY) were evaluated under various stress conditions. Additionally, prokaryotic transcriptome analysis was performed to identify the downstream stress-factors in WT and Δ uvrY. The results indicated that the Δ uvrY strain exhibited reduced tolerance to osmotic and acid - base stress compared with the WT and C-Δ uvrY. Furthermore, the deletion of uvrY in A. veronii significantly impaired persister formation and decreased resistance to multiple antibiotics, particularly tetracyclines and chloramphenicol. The transcriptome analysis revealed that the increased susceptibility of Δ uvrY to tetracyclines was accompanied by a significant down-regulation of efflux pump genes and NADH dehydrogenase I. STRING network analysis further demonstrated that the BarA-UvrY TCS is associated with genes encoding NADH dehydrogenase I and efflux pump. Additionally, efflux experiments and respiratory rate assays confirmed that the Δ uvrY strain exhibited reduced efflux pump activity and a low respiratory rate, establishing a clear correlation between these two processes. Collectively, BarA-UvrY TCS play a crucial role in AR and persister formation by mediating energy-dependent efflux mechanisms. This study provides mechanistic insights into the regulatory functions of UvrY and offers a theoretical foundation for developing novel strategies to control A. veronii infections and enhance antimicrobial interventions.