A comparison between the effects of a surfactant (chenodeoxycholamine) and freezing and thawing on some properties of the membrane of Pseudomonas aeruginosa

Abstract

Chenodeoxycholamine, a bile acid conjugated with a quaternary amine, increases the rate of swelling of cells of a strain of Pseudomonas aeruginosa suspended in 0.05 M Na–K phosphate buffer, pH 7.7. It also inhibits benzoate oxidase induction but only when the concentration of the buffer is increased. The rate of swelling in normal and treated cells apparently depends on the rate of influx of ions. Ion efflux may also occur in the presence of an oxidizable substrate. Freezing and thawing has effects similar to those of the drug. Low concentrations of ninhydrin or mercuric chloride inhibit the induction of benzoate oxidase. The inhibition is markedly decreased in drug-treated and frozen and thawed cells.