Vulnerability of nucleic acids in mutant staphylococci with impaired respiration

Mutants of Staphylococcus aureus with increased sensitivity to ultraviolet radiation

Nitrosoguanidine (NG) mutagenesis of Staphylococcus aureus resulted in the isolation of eight mutants exhibiting 3 to 28 times greater sensitivity to ultraviolet (UV) radiation. These mutants were further characterized by their ability to repair UV-irradiated bacteriophage, to act as recipients in the transduction of antibiotic resistance, and their sensitivity to NG. Based on the available data, six of these mutants are reduced in their ability to perform host-cell reactivation. One of the remaining two mutants may be deficient in post-replication repair.

DIFFERENTIATION BY IMMUNODIFFUSION AND BY QUANTITATIVE IMMUNOFLUORESCENCE BETWEEN 5-FLUOROURACIL-TREATED AND NORMAL CELLS FROM A TOXINOGENIC STAPHYLOCOCCUS AUREUS STRAIN

De Repentigny , J. (University of Montreal, Montreal, Quebec, Canada), S. Sonea, and A. Frappier . Differentiation by immunodiffusion and by quantitative immunofluorescence between 5-fluorouracil-treated and normal cells from a toxinogenic Staphylococcus aureus strain. J. Bacteriol. 88: 444–448. 1964.—Immunodiffusion and quantitative immunofluorescence can both detect antigenic changes produced by 5-fluorouracil (FU) in Staphylococcus aureus Wood 46 strain. When FU is added to the cultures in their logarithmic phase of growth, a number of bacterial antigens are no longer detectable by immuno-diffusion and the intensity of the total immuno-fluorescence of bacteria is diminished; thus, these antigens are either profoundly modified or no longer synthesized. Uracil and, less effectively, thymine can reverse the FU inhibitory effect on the synthesis of antigens, and the number of precipitin lines remains closer to controls. The immunochemical approach provides a new way of obtaining information on the action of this pyrimidine analogue on metabolic processes in pathogenic bacteria. Microscopic quantitative immunofluorescence seems to be adaptable to give indirect information on changes in the metabolism or synthesis or antigens of a single bacterial cell.