title: Incorporation of exogenous fatty acids protects Enterococcus faecalis from membrane-damaging agents.
abstract: Enterococcus faecalis is a commensal bacterium of the mammalian intestine that can persist in soil and aquatic systems and can be a nosocomial pathogen to humans. It employs multiple stress adaptation strategies in order to survive such a wide range of environments. Within this study, we sought to elucidate whether membrane fatty acid composition changes are an important component for stress adaptation. We noted that E. faecalis OG1RF was capable of changing its membrane composition depending upon growth phase and temperature. The organism also readily incorporated fatty acids from bile, serum, and medium supplemented with individual fatty acids, often dramatically changing the membrane composition such that a single fatty acid was predominant. Growth in either low levels of bile or specific individual fatty acids was found to protect the organism from membrane challenges such as high bile exposure. In particular, we observed that when grown in low levels of bile, serum, or the host-derived fatty acids oleic acid and linoleic acid, E. faecalis was better able to survive the antibiotic daptomycin. Interestingly, the degree of membrane saturation did not appear to be important for protection from the stressors examined here; instead, it appears that a specific fatty acid or combination of fatty acids is critical for stress resistance.
authors.affiliation: Department of Microbiology, University of Tennessee, Knoxville, Tennessee, USA.
authors.forename: Holly E
authors.initials: HE
authors.lastname: Saito
authors.affiliation: Department of Microbiology, University of Tennessee, Knoxville, Tennessee, USA.
authors.forename: John R
authors.initials: JR
authors.lastname: Harp
authors.affiliation: Department of Microbiology, University of Tennessee, Knoxville, Tennessee, USA efozo@utk.edu.
authors.forename: Elizabeth M
authors.initials: EM
authors.lastname: Fozo
mesh_terms: D000220:Adaptation, Biological; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001646:Bile; D001647:Bile Acids and Salts / Q000494:pharmacology; D002462:Cell Membrane / Q000737:chemistry* / Q000378:metabolism; D017576:Daptomycin / Q000494:pharmacology; D024881:Drug Resistance, Bacterial; D013293:Enterococcus faecalis / Q000737:chemistry* / Q000187:drug effects / Q000502:physiology*; D005227:Fatty Acids / Q000032:analysis / Q000378:metabolism / Q000493:pharmacokinetics*; D019787:Linoleic Acid / Q000494:pharmacology; D019301:Oleic Acid / Q000494:pharmacology
chemical_list: D000900:Anti-Bacterial Agents; D001647:Bile Acids and Salts; D005227:Fatty Acids; D019301:Oleic Acid; D019787:Linoleic Acid; D017576:Daptomycin