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.
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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.
View Article and Find Full Text PDFMale ICR Swiss mice (2 to 3 months old) were fed Candida albicans in their drinking water for 3 days, followed by no treatment, antibiotics in their drinking water (daily), or immunosuppressants given by intraperitoneal injection (two to three times weekly) over a 3- to 4-week period. The organs of animals were processed to determine the numbers of C. albicans and total aerobic bacteria per g of tissue.
View Article and Find Full Text PDFRibosomal resistance in the gentamicin producer organism Micromonospora purpurea.
Antimicrob Agents Chemother
August 1982
The mechanism of resistance of the gentamicin-producing organism Micromonospora purpurea was analyzed. Determination of minimal inhibitory concentrations revealed high resistance to the 4,6-substituted deoxystreptamine aminoglycosides amikacin, gentamicin, kanamycin, netilmicin, sisomicin, and tobramycin and also to lividomycin A and hygromycin B, but susceptibility to streptomycin, dihydrostreptomycin, paromomycin, and neomycin during all phases of the growth cycle. The nonproducing, closely related Micromonospora melanosporea was susceptible to these compounds.
View Article and Find Full Text PDFThe method of differential centrifugation in the sucrose density gradient (SDG) enabled one to trace the changes in the development of the seed and fermentation mycelium of the gentamicin-producing organism. Correlation between gentamicin distribution in the SDG and the culture productivity was found. It was shown that the culture grown under the optimal aeration and agitation conditions was characterized by formation of higher amounts of the mycelium in the 5th and 6th layers of the SDG.
View Article and Find Full Text PDFBy mutation and strain improvement techniques idiotrophs of Micromonospora purpurea, the gentamicin-producing organism, were obtained which require an exogenous source of 2-deoxystreptamine in order to produce gentamicin. Streptamine incorporation afforded a mixture of 2-hydroxygentamicin C as a complex of essentially the C1 and C2 components whereas 2-deoxystreptamine when incorporated by the same idiotroph afforded the same mixture of C1, C2 and C1a gentamicins as the parent (m1) organism. The 2-hydroxygentamicin C complex exhibited broad-spectrum antibiotic activity with an in vitro potency less than that for the gentamicin C complex, but with greater activity against selected gentamicin C resistant organisms.
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