Cis-2-Decenoic Acid Modulation of <em>Vibrio vulnificus</em> Biofilms

Vibrio vulnificus is a marine bacterial pathogen perpetrating severe wound and gastrointestinal infections in humans. The growing incidence of V. vulnificus infections and the widening ecological range of the species, closely linked to climate change trends, draw attention to an increasing need for methods to combat V. vulnificus infections without further augmenting the threat of antimicrobial resistance. The results presented herein highlight the ability of an unsaturated fatty acid diffusible signal factor, cis-2-decenoic acid (CDA), to influence the behavior of biofilms formed by a virulent human isolate strain of V. vulnificus (ATCC 27562). Results indicated that joint treatment of biofilms with 150 μM CDA and ciprofloxacin allowed for three-fold reduction in cell growth and ten-fold reduction in biofilm biomass (p < 0.05) at inhibitory ciprofloxacin concentrations of 1 mg/L and 2 mg/L, respectively. These concentrations were lower concentrations than those sufficient for inhibitory effects under treatment with ciprofloxacin alone (>4 mg/L). Additionally, it was observed that CDA treatment resulted in reduced cell densities in the stationary and early death phases of planktonic growth. Finally, another interesting facet of the data collected was that CDA treatment alone did not induce dispersal in V. vulnificus biofilms. This contrasts with findings previously reported for similar treatments of other bacterial species. Taken together, the results suggest that the planktonic and biofilm forms of V. vulnificus are responsive to CDA treatment, which increases antibiotic susceptibility and mediates multifaceted responses and mechanisms that merit further investigation and develop of applications that improve human and environmental health outcomes.