title: Capacity of the outer membrane of a gram-negative marine bacterium in the presence of cations to prevent lysis by Triton X-100.
abstract: Cells of marine pseudomonad B-16 (ATCC 19855) washed with a solution containing 0.3 M NaCl, 50 mM MgCl2, and 10 mM KCl (complete salts) could be protected from lysis in a hypotonic environment if the suspending medium contained either 20 mM Mg2+, 40 mM Na+, or 300 mM K+. When the outer double-track layer (the outer membrane) of the cell envelope was removed to yield mureinoplasts, the Mg2+, Na+ or K+, requirements to prevent lysis were raised to 80, 210, and 400 mM, respectively. In the presence of 0.1% Triton X-100, 220, 320, and 360 mM Mg2+, Na+ or K+, respectively, prevented lysis of the normal cells. Mureinoplasts and protoplasts, however, lysed instantly in the presence of the detergent at all concentrations of Mg2+, Na+, or K+ tested up to 1.2 M. Thus, the structure of the outer membrane appears to be maintained by appropriate concentrations of Mg2+ or Na+ in a form preventing the penetration of Triton X-100 and thereby protecting the cytoplasmic membrane from dissolution by the detergent. K+ was effective in this capacity with cells washed with complete salts solution but not with cells washed with a solution of NaCl, suggesting that bound Mg2+ was required in the cell wall membrane for K+ to be effective in preventing lysis by the detergent. At high concentrations (1 M) K+ and Mg2+, but not Na+, appeared to destabilize the structure of the outer membrane in the presence of Triton X-100.
mesh_terms: D001426:Bacterial Proteins / Q000378:metabolism; D001433:Bacteriolysis / Q000187:drug effects*; D002462:Cell Membrane / Q000187:drug effects; D002473:Cell Wall / Q000502:physiology; D008274:Magnesium / Q000494:pharmacology; D009995:Osmosis; D011092:Polyethylene Glycols / Q000494:pharmacology*; D011188:Potassium / Q000494:pharmacology; D011523:Protoplasts / Q000187:drug effects; D011549:Pseudomonas / Q000187:drug effects*; D000644:Quaternary Ammonium Compounds / Q000494:pharmacology*; D012964:Sodium / Q000494:pharmacology; D012995:Solubility; D014871:Water Microbiology
chemical_list: D001426:Bacterial Proteins; D000644:Quaternary Ammonium Compounds; D011092:Polyethylene Glycols; D012964:Sodium; D008274:Magnesium; D011188:Potassium