Exogenous Polyunsaturated Fatty Acids Impact Membrane Remodeling and Affect Virulence Phenotypes among Pathogenic Vibrio Species

Abstract

The pathogenic species (, , and) represent a constant threat to human health, causing foodborne and skin wound infections as a result of ingestion of or exposure to contaminated water and seafood. Recent studies have highlighted 's ability to acquire fatty acids from environmental sources and assimilate them into cell membranes. The possession and conservation of such machinery provokes consideration of fatty acids as important factors in the pathogenic lifestyle of species. The findings here link exogenous fatty acid exposure to changes in bacterial membrane phospholipid structure, permeability, phenotypes associated with virulence, and consequent stress responses that may impact survival and persistence of pathogenic species. Polyunsaturated fatty acids (PUFAs) (ranging in carbon length and unsaturation) supplied in growth medium were assimilated into bacterial phospholipids, as determined by thin-layer chromatography and liquid chromatography-mass spectrometry. The incorporation of fatty acids variably affected membrane permeability, as judged by uptake of the hydrophobic compound crystal violet. For each species, certain fatty acids were identified as affecting resistance to antimicrobial peptide treatment. Significant fluctuations were observed with regard to both motility and biofilm formation following growth in the presence of individual PUFAs. Our results illustrate the important and complex roles of exogenous fatty acids in the membrane physiology and virulence of a bacterial genus that inhabits aquatic and host environments containing an abundance of diverse fatty acids. Bacterial responses to fatty acids include, but are not limited to, degradation for metabolic gain, modification of membrane lipids, alteration of protein function, and regulation of gene expression. species exhibit significant diversity with regard to the machinery known to participate in the uptake and incorporation of fatty acids into their membranes. Both aquatic and host niches occupied by are rife with various free fatty acids and fatty acid-containing lipids. The roles of fatty acids in the environmental survival and pathogenesis of bacteria have begun to emerge and are expected to expand significantly. The current study demonstrates the responsiveness of ,, and to exogenous PUFAs. In addition to phospholipid remodeling, PUFA assimilation impacts membrane permeability, motility, biofilm formation, and resistance to polymyxin B.

Exogenous fatty acids alter phospholipid composition, membrane permeability, capacity for biofilm formation, and antimicrobial peptide susceptibility in Klebsiella pneumoniae

“…Recent studies from our laboratory have explored the various contributions of exogenous fatty acids on the physiology of Gram‐negative pathogens (Eder et al., ; Moravec et al., ). In addition to altering the membrane phospholipid constitution, notable changes to the MICs of antimicrobial peptides were observed, hinting toward potential therapeutic value.…”

Exogenous polyunsaturated fatty acids (PUFAs) promote changes in growth, phospholipid composition, membrane permeability and virulence phenotypes in Escherichia coli

“…No longer are fatty acids merely a carbon source destined for b-oxidation; they represent multipurpose molecules capable of nutritional value, membrane phospholipid remodeling, and signalmediated behavioral control. Previous studies from our laboratory have explored these phenomena in several medically important bacteria, including Vibrio species, Pseudomonas aeruginosa, Klebsiella pneumoniae, and Acinetobacter baumanii [1][2][3][4]; however, an analysis of the model organism E. coli had not been performed.…”

“…Permeability Assays. Three different membrane permeability assays were carried out to determine the effects of phospholipid remodeling in E. coli by following previously established procedures [2,3]. The rst assay monitored bacterial uptake of the hydrophobic compound crystal violet (CV).…”

“…The observed alteration to membrane permeability led to an investigation of the impact of fatty acids on antimicrobial peptide susceptibility, a phenomenon previous documented for several Gram-negative bacteria [1][2][3][4]. For these experiments, two antimicrobials (polymyxin B and colistin) with mechanisms of action that target membrane bilayers via biophysical intercalation were chosen to compare with an antibiotic (ampicillin) that relies on protein-mediated uptake for activity.…”

“…An emerging body of evidence has highlighted the expanded fatty acid handling characteristics of Gramnegative bacteria. The impacts of fatty acids acquired from growth media include phospholipid remodeling and phenotypes affecting growth and virulence [1][2][3][4]. The expanded utility of fatty acids magni es the relevance of environmental adaptation for bacteria, especially those that oscillate between host and aquatic niches.…”