The TPR family protein VPA1365 regulates biofilm matrix to promote biofilm formation in Vibrio parahaemolyticus

Vibrio parahaemolyticus is a notorious foodborne opportunistic pathogen capable of sensing external environmental signals to regulate its survival and virulence. In recent years, this pathogen has been increasingly detected in freshwater foods, indicating a distribution shift from its original marine reservoirs. Biofilm formation plays a crucial role in its adaptation ability from high-salt to low-salt environments. Here, we showed that VPA1365, a TPR family regulator, significantly promotes biofilm formation in V. parahaemolyticus. The Δvpa1365 mutant exhibited impaired biofilm formation under either low-salt (0.1 M NaCl) or high-salt (0.5 M NaCl) condition compared to that of the wild-type (WT) strain. The deletion of vpa1365 did not alter the flagella-mediated motility, however, it significantly reduced the metabolic activity of biofilm cells and production of key biofilm matrix components (exopolysaccharides, extracellular DNA, and extracellular proteins). Besides, the Δvpa1365 mutant exhibited lower expression levels of biofilm-related genes than that of the WT strain. All observed phenotypes were largely restored to WT levels in the complemented strain Δvpa1365-vpa1365. Therefore, our findings identify VPA1365 as a key regulator that enhances bacterial fitness via the positive regulation of biofilm formation. These insights deeply advance our comprehension of its environmental survival mechanisms and lay the groundwork for interventions to inhibit biofilm formation in V. parahaemolyticus.