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[Effect of the producer type on the nature of antibiotic fermentation].

Fermentation processes in production of bacitracin, a polypeptide antibiotic by Bacillus licheniformis, and oleandomycin, a macrolide antibiotic by Streptomyces antibioticus, were studied comparatively. It was shown that the antibiotic-producing actinomycete was characterized by a prolonged phase of growth retardation. The highest efficiency of the control actions was observed at the beginning of the fermentation. They were aimed at intensifying the substrate usage during the growth phase and activation of cell metabolism. Controlled cultivation of the Bacillus representative was based on its capacity of achieving the maximum growth rate possible under the certain conditions. Therefore, an increase in the quantity of the synthesized antibiotic was due, under such conditions, to inhibition of the culture growth by various means including lower mass exchange intensity.

Bacillus↗

[Effect of partial pressure of solute oxygen on the intensity of respiration of cultures of antibiotic producers].

It was shown possible to use feeding of hydrogen peroxide as a method for investigating the impact of dissolved oxygen concentrations on growth and development of microorganisms. The influence of pO2 on the respiration intensity was studied in penicillin- and erythromycin-producing cultures and it was found that dependence of the respiration intensity on pO2 had the form of a curve with saturation, at pO2 equal to zero the value of the culture respiration intensity being different from zero. A mathematical model accounting for the presence in the fermentation broth of microbial agglomerates with the average size depending on the agitation conditions is proposed for describing the relationships.

Air↗

[Transformation of anthracycline antibiotics and their semisynthetic derivatives as affected by the liver aldo-keto reductase of rats].

Formation of 13-dihydro derivatives of rubomycin (daunorubicin), carminomycin, doxorubicin and some of their semisynthetic derivatives under the effect of pure aldo-keto reductase from the rat liver was studied. Attachment of an oxy group to C-14 markedly retarded formation of the 13-dihydro derivatives while attachment of the bulky radicals to the same position prevented their formation. Binding of the anthracycline antibiotics to human serum albumin had no impact on the fermentative reaction rate. Rubomycin, carminomycin and doxorubicin significantly differed in their lipophilic properties and capacity for binding to serum albumin.

Alcohol Oxidoreductases↗

[Oxidation-reduction status of the culture medium during the biosynthesis of amphotericin B].

The possibility of potentiometric estimation of the oxidation-reduction state of the fermentation broth during production of amphotericin B was studied. It was shown that the reduction capacity of the fermentation broth was high and did not change significantly during the antibiotic biosynthesis. It contained electrochemically active compounds in amounts providing stable potentials on the indicator electrodes. Both the platinum and the glass redoxmetric electrodes not sensitive to changes in the level of oxygen dissolved in the fermentation broth might be used for measuring the oxidation potential of the fermentation broth. Investigation of the dynamics of the oxidation potential changing revealed that during the process of amphotericin B biosynthesis the potential changed within wide ranges and every stage of the culture development was characterized by particular direction of the potential changing. This allowed, in combination with other parameters of the process, estimation of physiological activity of the culture at any moment of its growth.

Amphotericin B↗

[Conditions for the standardization of the process of cephalosporin biosynthesis].

Dependence of the final results of cephalosporin biosynthesis on the parameters of the operating conditions and the design of fermentors was shown. The value of the specific power input for agitation had a significant effect on the biosynthetic process. An equation for estimating the final results of the biosynthetic process by the values of the operating conditions and the fermentor design parameters is presented.

Acremonium↗