RESISTANCE AND CROSS-RESISTANCE OF ESCHERICHIA COLI S MUTANTS TO THE RADIOMIMETIC AGENT PROFLAVINE

EFFECT OF HEAT AND PLATING MEDIUM ON SURVIVAL OF ESCHERICHIA COLI AFTER TREATMENT WITH RADIOMIMETIC CHEMICALS

Zampieri, Antonio (Palo Alto Medical Research Foundation, Palo Alto, Calif.), and Joseph Greenberg. Effect of heat and plating medium on survival of Escherichia coli after treatment with radiomimetic chemicals. J. Bacteriol. 89:931-936. 1965.-Survival of Escherichia coli strain S and its radioresistant mutant R(4) after treatment with mitomycin C, azaserine, nitrogen mustard, 1-methyl-3-nitro-1-nitrosoguanidine, nitrofurazone, and proflavine was studied. With all agents except proflavine, R(4) was more resistant than was S. Survival of strain S was greater on minimal glucose-salts medium than on Penassay (Difco), and greater on the latter than on Tryptone (Difco) agar; survival of S was greater when posttreatment incubation temperature was 45 C than when it was 37 C. Post-treatment plating medium or temperature had no effect on survival of R(4). Visible light did not affect survival of S or R(4). The survival curves of R(4) were exponential; those of S exhibited decreasing sensitivity with time of exposure. With proflavine, photoactivation by visible light was demonstrable, but there was no difference in survival between S and R(4). Survival of either strain was not affected by post-treatment plating medium or incubation temperature.

Genetic determination of resistance to acriflavine, phenethyl alcohol, and sodium dodecyl sulfate in Escherichia coli

Wild-type strains of Escherichia coli K-12 are resistant to acriflavine. Gene acrA(+) which determines resistance to acriflavine is located near the lac region of the chromosome. This gene determines not only resistance to basic dyes but also resistance to phenethyl alcohol. Acriflavine resistance was transmitted, together with phenethyl alcohol resistance, from a resistant Hfr strain to a sensitive recipient by mating. Reversion of the mutant gene acrA1 (phenotypically acriflavine-sensitive) to acriflavine resistance was accompanied by a change from phenethyl alcohol sensitivity to resistance, and conversely the revertants selected for phenethyl alcohol resistance were resistant to acriflavine. A suppressor mutation, sup-100, closely linked to the acr locus, suppresses the acrA1 gene (phenotypically acriflavine-resistant), but does not determine resistance to phenethyl alcohol and basic dyes other than acriflavine. The genetic change in the locus acrA1 to types resistant to basic dyes and phenethyl alcohol was accompanied by an increase in resistance to sodium dodecyl sulfate, a potent solvent of lipopolysaccharide and lipoprotein. It is suggested that gene acrA determines synthesis of a membrane substance. The system seemed to be affected strongly by the presence of inorganic phosphate.

Phenethyl Alcohol I. Effect on Macromolecular Synthesis of Escherichia coli

Rosenkranz, Herbert S. (Columbia University, New York, N.Y.), Howard S. Carr, and Harry M. Rose . Phenethyl alcohol. I. Effect on macromolecular synthesis of Escherichia coli . J. Bacteriol. 89: 1354–1369. 1965.—An investigation of the mode of action of phenethyl alcohol produced the following results. Phenethyl alcohol had no effect on the physicochemical properties of isolated deoxyribonucleic acid (DNA). The DNA isolated from phenethyl alcohol-treated bacteria had physicochemical properties identical with those of DNA isolated from normal cells. The metabolic functions most sensitive to the inhibitory action of phenethyl alcohol appeared to be the process of enzyme induction and, possibly, the synthesis of messenger ribonucleic acid. Phenethyl alcohol did not affect the polyuridylic acid-mediated synthesis of polyphenylalanine in a cell-free amino acid-incorporating system.