title: Role of ectoine in Vibrio cholerae osmoadaptation.
abstract: Vibrio cholerae is both an intestinal pathogen and a microbe in the estuarine community. To persist in the estuarine environment, V. cholerae must adjust to changes in ionic composition and osmolarity. These changes in the aquatic environment have been correlated with cholera epidemics. In this work, we study the response of V. cholerae to increases in environmental osmolarity. Optimal growth of V. cholerae in minimal medium requires supplementation with 200 mM NaCl and KCl. However, when the NaCl concentration is increased beyond 200 mM, a proportionate delay in growth is observed. During this delay in growth, osmotic equilibrium is reached by cytoplasmic accumulation of small, uncharged solutes that are compatible with growth. We show that synthesis of the compatible solute ectoine and transport of the compatible solute glycine betaine impact the length of the osmoadaptive growth delay. We also demonstrate that high-osmolarity-adapted V. cholerae displays a growth advantage when competed against unadapted cells in high-osmolarity medium. In contrast, low-osmolarity-adapted V. cholerae displays no growth advantage when competed against high-osmolarity-adapted cells in low-osmolarity medium. These results may have implications for V. cholerae population dynamics when seawater and freshwater and their attendant microbes mix.
authors.affiliation: Division of Geographic Medicine and Infectious Diseases, New England Medical Center, Boston, Massachusetts 02111, USA.
authors.forename: Kathryn J
authors.initials: KJ
authors.lastname: Pflughoeft
authors.forename: Katharine
authors.initials: K
authors.lastname: Kierek
authors.forename: Paula I
authors.initials: PI
authors.lastname: Watnick
mesh_terms: D000123:Acetyltransferases / Q000235:genetics / Q000378:metabolism; D000222:Adaptation, Physiological; D000599:Amino Acids, Diamino / Q000378:metabolism*; D000613:Aminobutyrates / Q000378:metabolism; D003470:Culture Media; D017353:Gene Deletion; D015964:Gene Expression Regulation, Bacterial; D006801:Humans; D009994:Osmolar Concentration; D011188:Potassium / Q000378:metabolism; D012965:Sodium Chloride / Q000494:pharmacology*; D014734:Vibrio cholerae / Q000187:drug effects / Q000235:genetics / Q000254:growth & development* / Q000502:physiology*
chemical_list: D000599:Amino Acids, Diamino; D000613:Aminobutyrates; D003470:Culture Media; C005959:2,4-diaminobutyric acid; D012965:Sodium Chloride; C045628:ectoine; D000123:Acetyltransferases; D011188:Potassium