Both Escherichia coli B and a proflavine-resistant mutant, E. coli B/Pr, took up the same amounts of proflavine when suspended in buffer containing the dye. In growth media, however, sensitive cells took up more proflavine than did resistant cells. Adding growth media or any one of several constituents of these media, including amino acids, glycerol, pyruvic acid, and metabolizable sugars, to resistant cells that had taken up proflavine in buffer caused them to lose the dye, but had less or no effect on sensitive cells. Certian salts caused an equal release of proflavine from resistant and sensitive cells. Proflavine released from resistant cells by glucose was not changed chemically. The effects of temperature and metabolic inhibitors suggest that proflavine uptake is a passive process but that its release may be an active one, dependent on metabolism. Glucose had more effect on the proflavine binding of E. coli B grown in a minimal medium than on that of cells grown in a complex medium. E. coli B was less susceptible to proflavine when growing in a minimal medium. The effects of other synthetic media on proflavine susceptibility of E. coli B were also studied. Deoxyribonucleic acid and envelopes from sensitive and resistant cells bound the same amounts of proflavine, and no difference was seen in the site of dye binding when sensitive and resistant cells that had taken up proflavine in buffer were sonically broken and fractionated. The results suggest that sensitive and resistant cells are equally permeable to proflavine but differ in the ease with which metabolites cause them to release bound proflavine. So far, however, these differences do not account completely for the ability of resistant cells to grow in high proflavine concentrations.

Journal Article↗

PubMed1968

Responses of a psychrophilic marine bacterium to changes in its ionic environment.

Explore the source record for details and available documents.

Bacteria↗

PubMed1968

Radioisotopic studies on the biosynthesis of the glyceryl diether lipids of Halobacterium cutirubrum.

Explore the source record for details and available documents.

Acetates↗

PubMed1968

Absence of normal cell wall constituents from the outer layers of Halobacterium cutirubrum.

Explore the source record for details and available documents.

Alanine↗

PubMed1966

Mechanism of dissolution of envelopes of the extreme halophile Halobacterium cutirubrum.

Onishi, H. (National Research Council, Ottawa, Ontario, Canada), and D. J. Kushner. Mechanism of dissolution of envelopes of the extreme halophile Halobacterium cutirubrum. J. Bacteriol. 91:646-652. 1966.-Envelopes of Halobacterium cutirubrum dissolved rapidly in media of low ionic strength. Heating partially inhibited breakdown, probably because of nonspecific protein coagulation rather than inactivation of a lytic enzyme(s). Dissolution of envelopes in water did not involve splitting of peptide bonds or protein-lipid bonds, or any extensive breakdown of carbohydrate polymers. Dissolution was increased by alcohols and urea, even at high salt concentrations, but was not affected by metabolic inhibitors. Thus, no evidence was found for a dilution-activated lytic enzyme that contributes to envelope breakdown. Cells of H. cutirubrum were stable in 2 m NaCl, but lysis occurred in 2 m KCl or NH(4)Cl. This lysis did not involve an extensive breakdown of the envelope. No evidence for different sites of Na(+), K(+), and NH(4) (+) action was obtained from the pattern of release of envelope constituents in different concentrations of these salts. Ultracentrifugation studies showed that adding salts to envelopes that had been dissolved in water led to a nonspecific reaggregation of envelope material. No difference was seen between the effects of KCl and NaCl, except at 3 to 4 m concentrations where KCl caused more aggregation. The preferential effect of Na(+) on intact cells is probably due to its ability specifically to prevent leakage rather than to an overall effect on envelope integrity.

Alcohols↗

PubMed1966

Contribution of protein and lipid components to the salt response of envelopes of an extremely halophilic bacterium.

Kushner, D. J. (National Research Council, Ottawa, Ontario, Canada), and H. Onishi. Contribution of protein and lipid components to the salt response of envelopes of an extremely halophilic bacterium. J. Bacteriol. 91:653-660. 1966.-Removal of protein from envelopes of Halobacterium cutirubrum by peptic digestion left residues that required little or no salt for stability. The salt requirement of envelopes was also lowered by incubation in 0.1 m MgCl(2), and could be lowered even further by digestion with trypsin or chymotrypsin in 0.1 m MgCl(2). Dissolution of envelopes in low salt concentrations made their protein more susceptible to attack by these and other proteolytic enzymes. Removal of lipids raised the requirement for divalent cations, particularly for Mg(++); it slightly increased the Na(+) requirement and did not affect the requirement for K(+). It was concluded that the requirement for high salt concentrations in extreme halophiles is due to mutual repulsion between negatively charged groups on proteins rather than to repulsion between negatively charged phosphate groups on the lipids. The latter act primarily as sites on which divalent cations, especially Mg(++) which is required in high concentrations by growing cells, are bound. In this manner, the phosphate groups support envelope structure.

Amino Acids↗

PubMed1964

Lysis and dissolution of cells and envelopes of an extremely halophilic bacterium.

Kushner, D. J. (National Research Council, Ottawa, Ontario, Canada). Lysis and dissolution of cells and envelopes of an extremely halophilic bacterium. J. Bacteriol. 87:1147-1156. 1964.-Envelopes of the extremely halophilic bacterium, Halobacterium cutirubrum, disintegrate in the absence of salt to form much smaller particles. Extensive proteolytic breakdown to compounds of low molecular weight is not involved in this process or in the lysis of cells in the absence of salt. NaCl is much more effective than KCl or NH(4)Cl in preserving the integrity of intact cells, but is only slightly more effective in preserving the integrity of mechanically prepared envelopes, of cells made permeable by treatment with acid, and of cells made permeable by formalin fixation followed by exposure to water. MgCl(2) is much more effective in preserving the integrity of these preparations than of intact cells. The results suggest that the exterior cell surface has sites specifically requiring Na(+) to maintain their integrity, whereas the interior surface has sites whose integrity is maintained at least as well by K(+) or NH(4) (+) as by Na(+).

Ammonium Chloride↗