Aeromonas hydrophila is an adaptable and dangerous member of a genus capable of colonizing and infecting many hosts. Inhabitants of various aquatic environments, A. hydrophila can adversely affect aquaculture and cause human disease. The aim of this study was to determine the extent of polyunsaturated fatty acid (PUFA) handling in A. hydrophila with regard to incorporation into membrane phospholipids and effects on permeability, growth, antimicrobial resistance, biofilm formation, and swimming motility. Extracted phospholipids from PUFA-supplemented cultures were examined for lipid modification using both thin-layer chromatography and ultra performance liquid chromatography-mass spectrometry, demonstrating partial incorporation of all tested PUFAs. Phenotypic characteristics were evaluated using assays that tested for biofilm formation, membrane permeability, swimming motility, and antibiotic susceptibility. Temperature-dependent effects on biofilm formation and swimming motility were observed, and exposure to certain PUFAs resulted in significant ( P < 0.005) increases to membrane permeability using a hydrophobic dye uptake assay. Importantly, several PUFAs caused substantial (up to 16-fold) lowering of minimum inhibitory concentrations (MICs) against the membrane-active cyclic peptides polymyxin B and colistin. These responses to exogenous PUFAs may predict cellular signaling capabilities that aid multi-host pathogenic bacteria in their diverse environmental interactions.
Grant et al. (Sat,) studied this question.