MUTAGENIC EFFECT OF ETHYL METHANESULFONATE ON A NON-ACID-FAST STRAIN OF MYCOBACTERIUM PHLEI

Ethyl methanesulfonate was used for the induction of three types of mutants in a non-acidfast strain of Mycobacterium phlei. A total of 20 auxotrophie mutants was isolated. The mutants were isolated mostly when using doses yielding higher survival of the cells of the basic suspension. The auxotrophic mutants isolated required mostly amino acids, two mutants required purines and three mutants required vitamins. By determining the frequency of spontaneous reversions, it was found that 9 auxotrophic mutants could be used for further genetic studies. These included the following phenotypes: isoleucine-, leucine-, lysine-, nicotinic acid-, pyridoxine-, and xanthine-. Seven scotochromogenic mutants were isolated after ethyl methanesulfonate treatment. One was ochre, the remaining six were orange. Six achromogenic mutants were detected. Spontaneous auxotrophic mutants, scotochromogenic and achromogenic mutants were not isolated. The treatment with 0.2 m ethyl methanesulfonate resulted in an increase in the frequency of STM-resistant mutants, the maximum phenotypic expression taking place after 72 hours cultivation in a liquid medium without the drug. The frequency of induced STM-resistant mutants varied within the range of 8.6.10-5-1.0.10-4 as compared with the frequency of spontaneous mutants 5.8.10-6-8.8.10-6. © 1969 Academia, nakladatelství Československé akademie věd.