[Effect of chemical defoaming agents on the mass exchange rate in the oxytetracycline biosynthesis process]. / Vliianie khimicheskikh penogasitelei na skorost' massobmena v protsesse biosinteza oksitetratsiklina.

The effect of chemical foam suppressors of various classes on the intensity of Streptomyces rimosus respiration, concentrations of dissolved oxygen and carbon dioxide and gas levels in the fermentation broth of oxytetracycline was studied. Its was shown that addition of the foam suppressors, as a rule, resulted in a decreased rate of the oxygen mass transfer due to the decreased surface of the phase contact gas-liquid. This decrease was not so significant as that in case of uninhibited intensity of the fermentation broth foaming. A different character of the effect of different foam suppressors on the biosynthetic process was noted. The effect of the foam suppressors was decreased by their regular addition in low amounts.

[Cytomorphological changes in a culture of Streptomyces rimosus, the producer of oxytetracycline, in the presence of different foam retardants]. / Tsitomorfologicheskie izmeneniia kul'tury Streptomyces rimosus--produtsenta oksitetratsiklina--v prisutstvii razlichnykh penogasitelei.

The data on the effect of chemical foam suppressors of various classes on the morphogenesis of 2 strains of Streptomyces rimosus are presented. Correlation between the age of the culture and its reaction to unfavourable conditions is confirmed. During the first 24 hours of the growth the culture is most sensitive to low aeration rates, addition of the foam suppressors, fat deficiency in the medium. Among the foam suppressors used propinol B-400 had the most significant effect on the cells: destruction of the cell coating, marked changes in the morphogenesis and nucleocytosis of the hyphae of the second generation responsible mainly for the antibiotic biosynthesis. A more active strain was more subject to the foam suppressor toxic effect.