[Biosynthesis of the antibiotic gramicidin S by a Bacillus brevis culture associated with a change in growth kinetics]. / Biosintez antibiotika gramitsidina S kul'turoi Bacillus brevis v sviazi s izmeneniem kinetiki rosta.

The effect of changes in the kinetics of growth on gramicidin S biosynthesis by Bacillus brevis var. G.-B. was studied. The synthesis of gramicidin S is induced when the specific growth rate decreases, whatever is the factor causing this decrease. As was found experimentally, only cells of a certain age can synthesize gramicidin S.

[Growth limitations and biosynthesis of gramicidin in Bacillus brevis var. G.-B]. / Limitatsiia rosta i biosintez gramitsidina s Bacillus brevis var. G.-B.

Gramicidin S biosynthesis was studied in Bacillus brevis var. G.-B. during its batch and continuous cultivation when the culture growth was limited with nutrient sources (glycerol, ammonium nitrogen, phosphate), oxygen deficiency and the action of a physical factor (a low temperature). The antibiotic biosynthesis was shown to be induced by a change in the growth rate caused by the action of any factor decelerating the growth. The authors propose a mathematical model for the antibiotic synthesis, biomass accumulation and the utilization of a substrate limiting the growth. The model is based on the age separation of cells. The model is analyzed in terms of optimizing the one-stage continuous cultivation process. The model allows one to calculate optimal conditions of the antibiotic synthesis in the process of one-stage continuous cultivation.

[Sporulation and crystal formation in Bacillus thuringiensis during growth limitation via nutrient sources]. / Sporuliatsiia i kristalloobrazovanie u Bacillus thuringiensis pri limitatsii rosta istochnikami pitaniia.

The object of the work was to study the effect of limiting concentrations of glucose, yeast extract, phosphorus, magnesium and potassium on the growth, spore formation and crystal formation in Bacillus thuringiensis subsp. galleriae. The deficiency of the above components was shown to interfere in no way with the processes of spore and crystal formation. However, the type of limiting substrate influenced the character of spore formation, the duration of different phases in the culture growth, the yield of spores and crystals, and their quality.