The mutagenic effect of ultraviolet radiation and nitrous acid on Mycobacterium phlei

Folia Microbiologica (Impact Factor: 1.15). 02/1966; 11(3):163-8. DOI: 10.1007/BF02901427
Source: PubMed

ABSTRACT Lethal and mutagenic effects of nitrous acid and UV radiation onMycobacterium phlei were studied Three auxotrophic strains of the PA strain ofMycobacterium phlei were obtained: ala-, his-, and gly- (ser-) INHr Bods of the his- strain grown in liquid media are longer to filamentous as compared with cells of the prototrophic PA strain grown in the
same media, whereas cells of the gly- (ser-) INHr mutant are shorter to coccobacillary. Cells of the ala- strain are characterized by their various length from normal to coccobacillary. The auxotrophic strains obtained differ from
each other by a frequency of spontaneous reversions to prototrophy. The his- strain is the most stable, a frequency of spontaneous reversions to prototrophy being 10-9. The gly- (ser-) INHr strain reverts spontaneously to prototrophy with a frequency of 10-8 to 10-7. The ala- strain spontaneously reverting with a frequency of 10-5 is the most labile. The auxotrophic mutants obtained do not differ from the original prototrophic strain in the other properties

A change in a frequency of INH and STM-resistant mutants was also studied. It was found that under the influence of UV radiation
a frequency of INH-resistant mutants increases 43 to 80 fold as compared with a frequency of spontaneous mutations, this latter
being about 2.6 × 10-6. No substantial increase in a frequency of STM-resistant mutants was found using UV irradiation under the given experimental
conditions; their spontaneous frequency equals to 9.0 × 10-9 to 2.0 X 10-8.

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    ABSTRACT: The effect of nitrosoguanidine on the induction of three types of mutagenic changes inMycobacterium phlei PA was studied. The mutagenic changes included: change of prototrophy to auxotrophy, conversion of sensitivity to isoniazide to resistańce and sensitivity to streptomycin to resistance. The induction of auxotrophic mutants was successful especially when using NTG at a concentration of 1000 μg/ml. A total of 100 auxotrophs was obtained out of which only 13 were sufficiently stable to be used in further studies. Amino acid requirements especially the glycine−(serine−) type characterized more than half of all auxotrophic mutants obtained. A group of mutants requiring purines also included a high number of mutants. A considerable spontaneous reversion frequency was found in both groups of auxotrophs. The kinetics of the induction of INH-resistant mutants by nitrosoguanidine at a concentration of 1000 μg/ml was studied and a high induction of these mutants, particularly at high lethal effect of the mutagen found. The mutability of the STMr marker was relatively low in the present model microorganism as compared with the two markers mentioned earlier.
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