[Lethal and mutagenic action of N-nitroso-N-methylbiuret on the producers of levorin, amphotericin and mycoheptin].

The lethal and mutagenic effect of N-nitrozo-N-methylbiuret (NMB) on the organisms producing levorin, amphotericin B and mycoheptin was studied. The mutagen effect depended on the dose, culture and physiological state of the spores. NMB had a low mutagenic effect on the levorin-producing organism characterized by high activity and genetic homogenicity with respect to the colony morphology and antibiotic production.

[Comparative study of the action of streptomycin on the variability of levorin and amphotericin B producers].

The study of the effect of streptomycin on viability of Act. levoris, strain LIA=0868 producing levorin and Act. nodosus, strain LIA-0861 producing amphotericin B showed that streptomycin had a lethal effect which increased with increasing of its concentration from I to 6 gamma/ml.