Exogenous polyunsaturated fatty acids (PUFAs) alter phospholipid composition, membrane permeability, biofilm formation and motility in Acinetobacter baumannii

Abstract

Acinetobacter baumannii is a ubiquitous multidrug-resistant bacteria that is found on a variety of surfaces, including skin, hair and soil. During the past decade, A. baumannii has emerged as a significant cause of nosocomial infections in the United States. Recent studies have highlighted the ability of some bacteria to utilize a wide variety of fatty acids as a membrane remodelling strategy. Considering this, we hypothesized that fatty acids may have an effect on the emerging pathogen A. baumannii. Thin-layer chromatography indicated structural alterations to major phospholipids. Liquid chromatography/mass spectrometry confirmed the assimilation of numerous exogenous polyunsaturated fatty acids (PUFAs) into the phospholipid species of A. baumannii. The incorporation of fatty acids affected several bacterial phenotypes, including membrane permeability, biofilm formation, surface motility and antimicrobial peptide resistance.

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.…”

“…Antimicrobial Peptide Susceptibility Assay. A previously established protocol was used to determine the effect that PUFA exposure has on antimicrobial peptide susceptibility in E. coli [2,4]. Cultures were grown to logarithmic phase in CM9 minimal medium in the presence or absence of one of the seven PUFAs at a concentration of 300 µM.…”

“…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.…”