Effects of Perfluorooctanoic Acid (PFOA) on Colony Growth, Bioluminescence, and Swarming Motility of Vibrio campbellii and Quorum-Sensing Defective Mutants

Widespread environmental contamination by perfluoroalkyl and polyfluoroalkyl substances (PFAS) is raising particular concerns. PFAS are remarkably resistant to microbial degradation and have a profound impact on the structure and function of microbial communities. In this study, we analyzed the effect of perfluorooctanoic acid (PFOA) on bacterial quorum sensing, a communication process that in marine Vibrio species regulates biofilm formation and dissolution, virulence factors, swimming/swarming motility and bioluminescence. A system to continuously monitor bioluminescence during the growth on agar medium of Vibrio campbellii BB120 and isogenic luxS-, cpsA- and luxM-defective mutants, unable to synthesize, respectively, the autoinducers AI-2, CAI-1, and HAI-1, was utilized. By this system, we found that PFOA has dramatic effects on bacterial growth on agar and light emission kinetics, with specific effects in the different strains depending on the set of the autoinducers produced. Furthermore, we found that PFOA inhibited swarming motility in cqsA- and luxM-defective mutants which exhibited a very robust swarming phenotype in the absence of PFOA due to the lack of CAI-1 or HAI-1 that inhibit motility. The inhibitory effect on motility could be due to increased adherence of bacterial colonies to the agar substrate caused by the presence of PFOA. These results, although obtained in an in vitro system, suggest that PFOA may strongly interfere with bacterial growth kinetics and quorum sensing-regulated responses.