Permeability of Bacteria to Inorganic Cations. A Comparison between a Psychrophilic Achromobacter Strain and Escherichia coli

Abstract

The permeability of a psychrophilic Achromohacter strain to the chlorides of Na, K, Mg and Ca was investigated with light-scattering technique. Comparisons, were made with cells of Escherichia coli B. Cells of both strains suspended in w,ater were plasmolyzed by 0.1 or 0.2 M solutions of MgCfe or CaCl^ "without subsequent deplasmolysis. NaCI or KCI aiso plasmolyzed the cells, but deplasmolysis foliowed. When suspended in growth medium, E. coli became completely deplasmolyzed,, whereas the psychrophile still excluded MgClj and CaClg to a great extent. The plasnaolysis and deplasmolysis were reversible. Electron micrographs of the psychrophile exposed to CaCl2 confirmed the presence of plasnaolysis.

Calcium Uptake by a Psychrophilic Achromobacter Strain

“…Therefore, it seems that no passive diffusion of calcium ions into the cells takes place either. These conclusions agree fully with those drawn in the previous article (Ledebo and Ljunger 1973).…”

“…Aehromobaeter strain 102, a laboratory strain, was used. Its psychrophilic growth characteristics have been studied earlier (Ledebo and Ljunger 1973). Under the present conditions growth was obtained at 0°C, the optimum temperature was around 25°C and the maximum around 33°C.…”

“…The experiments were conducted to find out with what part of the cells the calcium ions are associated. Based on the results of previous experiments (Ledebo and Ljunger 1973), the ions were assumed not to be inside the cells. However, the possibilities of active transport and simple diffusion are considered as well as that of binding to cell components.…”

“…Sodium ions have been shown to penetrate the cell membranes of many species freely (Schultz and Solomon 1961, Takacs et al 1964, Matula and MacLeod 1969. The Achromobacter cells are permeable to sodium ions according to the same type of measurements that indicate that calcium ions are excluded (Ledebo and Ljunger 1973). TJie constant or moderately increased uptake of sodium ions after the heat or toluene treatment suggests that the sodium ions have access to the cell interior already before these treatments.…”

“…In a previous article the relationship between a psychrophilic bacterium and calcium ions was studied. Thelightscattering capacity of an Achromobacter strain in calcium solutions was registered and compared to that of Escherichia coli (Ledebo and LJunger 1973). The experiments indicated that calcium ions were to a large extent excluded from the psychrophile, since the cells remained plasmolyzed in calcium solutions.…”