title: Salt requirements in the denitrifying bacterium Pseudomonas nautica 617.
abstract: Pseudomonas nautica 617, which was isolated from superficial marine sediment, was found to require sodium for growth. Growth also appeared to be sensitive to the divalent cation, Mg2+, the presence of which, together with that of Na+, was necessary for achieving maximal growth. We investigated cell capacity to resist lysis after washing with either 0.05 M MgCl2 or 0.5 M NaCl, by monitoring suspension optical density changes as well as the release of ultraviolet absorbing material. Mg2+ turned out to play a significant role in stabilizing the structure of the cell envelope. Respiratory activity was also sensitive to ionic environment. With cells washed with 0.05 M MgCl2 and suspended in 0.05 M Tris buffer, the respiration rate, assessed by N2O evolution, was 15% of that measured in artificial sea water. Upon addition of 0.5 M Na+, nitrous oxide production rose to 32% of the reference level. The dinitrification rate was fully restored by further addition of 0.05 M Mg2+. K+ alone had almost no effect, but when added with Na+, the rate of denitrification increased to 45%.
authors: Centre d'Océanologie de Marseille, Faculté des Sciences de Luminy, Marseille.
authors: P
authors: P
authors: Bonin
authors: M
authors: M
authors: Gilewicz
authors: M
authors: M
authors: Denis
authors: J C
authors: JC
authors: Bertrand
mesh_terms: D001433:Bacteriolysis / Q000187:drug effects; D008274:Magnesium / Q000494:pharmacology*; D008386:Marine Biology; D009609:Nitrous Oxide / Q000378:metabolism*; D011549:Pseudomonas / Q000254:growth & development* / Q000378:metabolism; D012964:Sodium / Q000494:pharmacology*
chemical_list: D012964:Sodium; D008274:Magnesium; D009609:Nitrous Oxide