[Effect of aeration and agitation conditions on gentamycin biosynthesis].

The study on the relation between the production of gentamicin and the conditions of aeration and agitation of the fermentation broth showed the advisability of the control of these parameters with respect to the maximum rate of the oxygen uptake. Possible scaling-up of the process of gentamicin biosynthesis was shown with the use of the expression: (formula: see text).

[Oxidative-reductive activity of the mycelium as a criterion for assessing inoculate quality in gentamycin biosynthesis].

The development of the seed mycelium at various stages and temperatures was studied with the method of methylene blue decolorization characterizing the respiration level of the culture and its oxidation-reduction (dehydrogenase) activity. Relationship between the time of methylene blue decolorization by the seed mycelium, the quantity of the inoculum transferred from one stage to the other and the temperature of cultivation was shown. The seed mycelium decolorizing methylene blue within 2 minutes was most productive at the biosynthetic stage irrespective of the growth period, biomass volume, cultivation temperature and volume of the inoculum transferred from one stage to the other.

[Significance of pH for the growth of the sisomicin producer and biosynthesis of the antibiotic].

Dependence of the mycelium growth and sisomycin production on the pH values of the fermentation broth was studied in cultures of various ages for 6 hours with the method of pH control within the preset levels. It was shown that the values of pH within the range of 7.25 - 7.

[Development of a gentamicin producer under different culture conditions studied by a method of differential centrifugation of the mycelium in a saccharose density gradient].

The 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.

[Dependence of the component makeup of the gentamicin complex on Micromonospora purpurea var. violacea 1935 cultivation conditions].

Dependence of biosynthesis of gentamicin and vitamin B12 on complex and "synthetic" media under conditions of decreased aeration, increased phosphorus levels and non-optimal content of carbon source was studied. The decreased levels of vitamin B12 production under conditions of the non-optimal content of the carbon source and increased phosphorus levels in the medium resulted in decreased production of the antibiotic complex as a whole and decreased relative content of the most methylated gentamicins C1 and C2 in the complex. Decreased aeration lowered the mycelium productivity with respect to the antibiotic production without changing the ratio of the components in the complex and the level of vitamin B12 production.

[Role of cobalt in the biosynthesis of the components of the gentamicin complex].

It was shown that addition of cobalt ions or vitamin B12 to the fermentation medium resulted in an increase in the level of gentamicin accumulation, the relative content of the most methylated components C1 and C2 in the gentamicin complex being increased, while the content of the least methylated components CIa and "minors" decreased. Addition of sulphodimezine lowered the gentamicin biosynthesis rate and the relative content of gentamicins C1 and C2. It was supposed that cobalt stimulated the B12-dependent synthesis of methionine, being the source of the methyl groups for biosynthesis of the methylated components of gentamicin complex.

[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.

[Effect of cobalt on the growth of a Micromonospora purpurea var. violacea 1935 culture and on the biosynthesis of gentamincin].

The effect of cobalt on growth of Micromonospora purpurea var. violacea 1935 and biosynthess of gentamicin in complex soy-bean meal or "synthetic" gelatin medium was studied. In optimal concentrations cobalt increased the activity level of the culture fluid almost 6 times in both media having practically no effect on the amount of the mycelium formed.