Abstract
BackgroundPseudomonas aeruginosa, a common opportunistic pathogen, is known to cause infections in a variety of compromised human tissues. An emerging mechanism for microbial survival is the incorporation of exogenous fatty acids to alter the cell’s membrane phospholipid profile. With these findings, we show that exogenous fatty acid exposure leads to changes in bacterial membrane phospholipid structure, membrane permeability, virulence phenotypes and consequent stress responses that may influence survival and persistence of Pseudomonas aeruginosa.ResultsThin-layer chromatography and ultra performance liquid chromatography / ESI-mass spectrometry indicated alteration of bacterial phospholipid profiles following growth in the presence of polyunsaturated fatty acids (PUFAs) (ranging in carbon length and unsaturation). The exogenously supplied fatty acids were incorporated into the major bacterial phospholipids phosphatidylethanolamine and phosphatidylglycerol. The incorporation of fatty acids increased membrane permeability as judged by both accumulation and exclusion of ethidium bromide. Individual fatty acids were identified as modifying resistance to the cyclic peptide antibiotics polymyxin B and colistin, but not the beta-lactam imipenem. Biofilm formation was increased by several PUFAs and significant fluctuations in swimming motility were observed.ConclusionsOur results emphasize the relevance and complexity of exogenous fatty acids in the membrane physiology and pathobiology of a medically important pathogen. P. aeruginosa exhibits versatility with regard to utilization of and response to exogenous fatty acids, perhaps revealing potential strategies for prevention and control of infection.
Highlights
Pseudomonas aeruginosa, a common opportunistic pathogen, is known to cause infections in a variety of compromised human tissues
Polyunsaturated fatty acid (PUFA) exposure results in accelerated growth and altered phospholipid profiles of Pseudomonas aeruginosa The effect of PUFAs on P. aeruginosa phospholipids was investigated by growing bacteria in the presence and absence of micromolar concentrations of each fatty acid
Collectively, our findings emphasize the role that fatty acids may play in bacterial physiology, for pathogens with the ability to utilize fatty acids for enhanced virulence and survival
Summary
Pseudomonas aeruginosa, a common opportunistic pathogen, is known to cause infections in a variety of compromised human tissues. An emerging mechanism for microbial survival is the incorporation of exogenous fatty acids to alter the cell’s membrane phospholipid profile. With these findings, we show that exogenous fatty acid exposure leads to changes in bacterial membrane phospholipid structure, membrane permeability, virulence phenotypes and consequent stress responses that may influence survival and persistence of Pseudomonas aeruginosa. The ability of P. aeruginosa to thrive in diverse environments can be partially explained by its tremendous metabolic capabilities, allowing utilization of numerous substrates [1, 2] Many of these molecules have been identified to be nutritional cues, serving as signals to guide bacterial behavior (motility, biofilm, antibiotic resistance) [3,4,5]. Fatty acids have influenced motility, gene expression and survival [14,15,16,17,18], while inhibitory action of polyunsaturated fatty acids have been documented in several pathogens [19,20,21]
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