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

BACKGROUND: The utilization of exogenous fatty acids by Gram-negative bacteria has been linked to many cellular processes, including fatty acid oxidation for metabolic gain, assimilation into membrane phospholipids, and control of phenotypes associated with virulence. The expanded fatty acid handling capabilities have been demonstrated in several bacteria of medical importance; however, a survey of the polyunsaturated fatty acid responses in the model organism Escherichia coli has not been performed. The current study examined the impacts of exogenous fatty acids on E. coli. RESULTS: All PUFAs elicited higher overall growth, with several fatty acids supporting growth as sole carbon sources. Most PUFAs were incorporated into membrane phospholipids as determined by Ultra performance liquid chromatography-mass spectrometry, whereas membrane permeability was variably affected as measured by two separate dye uptake assays. Biofilm formation, swimming motility and antimicrobial peptide resistance were altered in the presence of PUFAs, with arachidonic and docosahexaenoic acids eliciting strong alteration to these phenotypes. CONCLUSIONS: The findings herein add E. coli to the growing list of Gram-negative bacteria with broader capabilities for utilizing and responding to exogenous fatty acids. Understanding bacterial responses to PUFAs may lead to microbial behavioral control regimens for disease prevention.

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

Klebsiella pneumoniae represents a major threat to human health due to a combination of its nosocomial emergence and a propensity for acquiring antibiotic resistance. Dissemination of the bacteria from its native intestinal location creates severe, complicated infections that are particularly problematic in healthcare settings. Thus, there is an urgency for identifying novel treatment regimens as the incidence of highly antibiotic-resistant bacteria rises. Recent findings have highlighted the ability of some Gram-negative bacteria to utilize exogenous fatty acids in ways that modify membrane phospholipids and influence virulence phenotypes, such as biofilm formation and antibiotic resistance. This study explores the ability of K. pneumoniae to assimilate and respond to exogenous fatty acids. The combination of thin-layer chromatography liquid chromatography-mass spectrometry confirmed adoption of numerous exogenous polyunsaturated fatty acids (PUFAs) into the phospholipid species of K. pneumoniae. Membrane permeability was variably affected as determined by two dye uptake assays. Furthermore, the availability of many PUFAs lowered the MICs to the antimicrobial peptides polymyxin B and colistin. Biofilm formation was significantly affected depending upon the supplemented fatty acid.

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

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.