Rosmarinic Acid and Sodium Citrate Have a Synergistic Bacteriostatic Effect against Vibrio Species by Inhibiting Iron Uptake

New strategies are needed to combat multidrug-resistant bacteria. The restriction of iron uptake by bacteria is a promising way to inhibit their growth. We aimed to suppress the growth of bacterial species by inhibiting their ferric ion-binding protein (FbpA) using food components. Twenty spices were selected for the screening of FbpA inhibitors. The candidate was applied to antibacterial tests, and the mechanism was further studied. An active compound, rosmarinic acid (RA), was screened out. RA binds competitively and more tightly than Fe to VmFbpA, the FbpA from , with apparent values of 8 μM vs. 17 μM. Moreover, RA can inhibit the growth of to one-third of the control at 1000 μM. Interestingly, sodium citrate (SC) enhances the growth inhibition effect of RA, although SC only does not inhibit the growth. The combination of RA/SC completely inhibits the growth of not only at 100/100 μM but also the vibriosis-causative pathogens and , at 100/100 and 1000/100 μM, respectively. However, RA/SC does not affect the growth of . RA/SC is a potential bacteriostatic agent against species while causing little damage to indigenous gastrointestinal bacteria.