Evidence for the release at low salt concentration of a lipid–protein–carbohydrate complex from isolated envelopes and whole cells of a marine pseudomonad

Abstract

The effect of divalent cations on the turbidity and pH of suspensions of isolated cell envelopes of a marine pseudomonad has been examined. As the concentration of Mg2+, Ca2+, or Mn2+ was increased the turbidity and pH of the suspensions increased. A concentration of 0.010 M of divalent cations produced the same turbidity in a suspension of cell envelopes as 1.0 M NaCl. The envelopes released soluble non-dialyzable material (Ndf) when suspended in 0.01 M NaCl but not when suspended in 0.001 M solutions of the divalent cations. Whole cells of the marine pseudomonad released an Ndf when suspended in 0.5 M sucrose. The Ndf from both cells and envelopes contained lipid, protein, and carbohydrate. Analytical ultracentrifugation of the Ndf from both cells and envelopes revealed the presence of only one major component with a sedimentation coefficient of 9.7 ± 0.07. Electrophoresis of Ndf gave rise to a component which stained for carbohydrate and another which stained for protein. Both moved to the anode.