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, it was demonstrated that L-Cysteine (L-Cys) showed an inhibitory effect on the growth of V. parahaemolyticus, with a minimum inhibitory concentration of 7.5 mM. Microscopic observation and viability assay revealed that L-Cys compromised bacterial membrane integrity, ultimately leading to cell death. Transcriptomic and biochemical analyses showed that L-Cys induced the reactive oxygen species (ROS) by inhibiting terminal respiratory oxidases and key antioxidant enzymes of superoxide dismutase and glutathione reductase. Also, L-Cys disrupted metabolic processes of sulfur assimilation, one-carbon metabolism, β-oxidation, and nucleotide biosynthesis, which compromised cellular repair and survival mechanisms. The inhibition of L-Cys on V. parahaemolyticus was primarily attributed to the hydrogen sulfide generated by L-Cys metabolism, followed by an increase in ROS. In addition to its antibacterial effect, L-Cys also effectively reduced the bacterial swimming motility. Finally, L-Cys demonstrated broad-spectrum inhibitory effects on other pathogenic Vibrio spp. Our findings demonstrated that L-Cys is a promising antimicrobial agent that induces ROS-mediated membrane disruption, with the advantages of cost-effectiveness and environmental safety in the control of vibriosis.IMPORTANCEMultidrug-resistant Vibrio parahaemolyticus poses a severe threat to mariculture sustainability and public health. Conventional antibiotics exacerbate antimicrobial resistance; therefore, in this study, we selected L-cysteine (L-Cys) as a potent inhibitor of V. parahaemolyticus, featuring cost-effectiveness, environmental safety, and ease of large-scale production. L-Cys is metabolized into hydrogen sulfide, and the latter triggers ROS burst, and it can also disrupt metabolic processes of sulfur assimilation, one-carbon metabolism, β-oxidation, and nucleotide biosynthesis. Besides, L-Cys also significantly reduced the bacterial swimming motility. Moreover, L-Cys suppresses the growth of other pathogenic Vibrio spp., offering a novel agent for vibriosis control.