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At least 271 records · Page 15Linked to original sources
PubMed1976

[Pleiotropic effect of the mutation of streptomycin resistance in Micromonospora purpurea var. violacea].

Variation of different features of populations of streptomycin-sensitive and streptomycin-resistant forms of M. purpurea var. violacea, an organism producing gentamicin was studied. The population of the initial streptomycin-sensitive culture was characterized by high homogeneity with respect to the cultural, morphological and some physiological properties. The variation of the features, such as the colony size, pigment formation, auxotrophic mutations, antibiotic production significantly increased in populations grown on media with streptomycin. Mutants differing from the initial strain by a complex of cultural, morphological and physiological features and in particular the antibiotic production were isolated from populations of the streptomycin-resistant variants.

Culture Media↗
PubMed1977

[Effect of different forms of nitrogen in the biosynthesis of gentamicin by a Micromonospora purpurea var. violacea 1935 culture].

The effect of different inorganic sources of reduced and oxidized nitrogen on biosynthesis of gentamicin was studied. It was shown that both the ammonium and the nitrate nitrogen were consumed by the antibiotic-producing organism. Out of all the salts tested only ammonium sulfate stimulated the biosynthesis of gentamicin. The positive role of this salt was due to both the ammonium and the sulfogroup, since the presence of the sulfogroup alone in sodium sulfat, magnesium or sulfuric acid resulted only in partial stimulation of gentamicin biosynthesis. Simultaneous addition of sulfuric acid ammonium nitrate which suppressed the antibiotic biosynthesis when used alone was equal to introduction of ammonium sulfate.

Ammonium Sulfate↗
PubMed1990

[Phosphate regulation of the processes of growth and biosynthesis of gentamicin in Micromonospora purpurea var. violaceae].

The influence of orthophosphate on isogenic strains of the gentamicin-producing organism with various levels of the antibiotic production was studied. An increase in the content of inorganic phosphate in the medium led to inhibition of the growth and gentamicin biosynthesis in all the strains: the low-active strains were more stable to the effect of the phosphate as compared to the highly active strains. Heterogeneity of the population of the strains was shown in respect of decreasing the growth rate and the level of the antibiotic biosynthesis inhibition in the presence of orthophosphate. Among the phosphate low-controllable forms there was a high number of low-active variants while among the clones with retarded growth and decreased production of the antibiotic there was a high number of productive variants. Inverse relationship between the antibiotic production level and the level of lability to the effect of inorganic phosphate was observed in the mutants of the gentamicin-producing organism.

Colony Count, Microbial↗