ABSTRACT
The methylotrophic bacterium Pseudomonas methanolica was shown to be very resistant to the bactericidal and mutagenic action of UV irradiation. The activity of reparation processes after UV irradiation was also detected as well as a weak photoreactivating activity in P. methanolica. The decrease in the survival rate of irradiated cells under the action of caffeine and acriflavine, reparation inhibitors, is indicative of the activity of the excision reparation systems and, possibly, the recombination branch of postreplicative reparation. No activity of the inducible reparation system was found. It has been concluded that the elevated resistance of P. methanolica cells to the bactericidal and mutagenic action of short-wavelength UV irradiation is associated with the activity of the reparation systems.
Subject(s)
Mutation , Pseudomonas/radiation effects , Ultraviolet Rays , Acriflavine/pharmacology , Benzoates/pharmacology , Caffeine/pharmacology , Cell Division/drug effects , Cell Division/radiation effects , Drug Combinations/pharmacology , Nalidixic Acid/pharmacology , Pseudomonas/drug effects , Pseudomonas/genetics , Radiation ToleranceABSTRACT
The correlation was studied between the elevated resistance of Pseudomonas methanolica, a facultative methylotroph, to the bactericidal action of UV (254 nm) and the content of a pink pigment in this organism. Absorption spectra of cell extracts containing the pigment were recorded. The ethanol and acetone extracts had two absorption maxima at 420-430 and 500-510 nm, respectively, which was typical of carotenoids. The culture with the pigment and its variant without the pigment had nearly identical survival rates. Therefore, the elevated resistance of P. methanolica cells seems to stem from the activity of DNA reparation cellular systems rather than from the presence of carotenoid pigments in the cells.
