L-cysteine inhibited the growth of Vibrio parahaemolyticus via increasing the ROS level

The emergence of multidrug-resistant Vibrio parahaemolyticus poses a severe threat to mariculture sustainability, highlighting the urgent need for eco-friendly antimicrobial agents. In this study, we demonstrated that L-Cysteine (L-Cys) functions as an inhibitor of V. parahaemolyticus, with a minimum inhibitory concentration of 7.5 mM. Microscopic observation and viability assays revealed that L-Cys compromises bacterial membrane integrity, ultimately leading to cell death. Further investigation indicated that the antibacterial effect is primarily attributed to the intracellular production of hydrogen sulfide (H2S) generated by L-Cys metabolism. Transcriptomic and biochemical analyses showed that L-Cys induced metabolic reprogramming by suppressing fatty acid {beta}-oxidation, one-carbon metabolism, and antioxidant enzymes. This disruption of redox homeostasis results in accelerated accumulation of reactive oxygen species (ROS). In addition to its antibacterial effect, L-Cys also effectively reduced the virulence factor of bacterial motility. Finally, L-Cys demonstrated broad-spectrum antimicrobial activity against other pathogenic Vibrio species, including V. alginolyticus and V. anguillarum. Our findings suggest that L-Cys is a promising antimicrobial agent inducing ROS to mediate membrane disruption, with the advantages of cost-effectiveness and environmental safety for controlling vibriosis. ImportanceVibrio parahaemolyticus is a significant pathogen in aquaculture and a common cause of seafood-borne gastroenteritis worldwide. The increasing prevalence of antibiotic-resistant strains of this bacterium highlights the need for alternative control agents. This study shows that L-cysteine (L-Cys) inhibits the growth of V. parahaemolyticus. Our data indicate that L-Cys is metabolized to produce hydrogen sulfide, which contributes to the accumulation of ROS and disrupts bacterial membrane integrity. Additionally, L-Cys reduces bacterial motility and shows inhibitory effects against other Vibrio species. These findings suggest that L-Cys may represent a useful agent for managing Vibrio infections in aquaculture settings.