[Comparative electron microscopic study of Bacillus thuringiensis cells grown in a chemostat]. / Sravnitel'noe élektronno-mikroskopicheskoe issledovanie kletok Bacillus thuringiensis, vyrashchennykh v khemostate.

It has been shown that the culture of Bacillus thuringiensis subsp. gall. 69-6 dissociates into R- and S-variants in chemostat. Although under some conditions the sporogenesis and the synthesis of S-variant toxin began two hours earlier than these processes in R-variant cells which were observed, respectively, after 10 or 12 hours from the beginning of the experiment, the intensities of sporogenesis and toxin production as well as the exit of spores and toxin excretion from cells were similar after 24 hours. The resistance to the bacteriophage present in chemostat was the advantage of S-variant cells. The data obtained by electron microscopy indicate that the phagoresistance is caused by the structural organization of the S-variant cell wall. Its peptidoglycan component is thin and is distinguished by crumb structure. By means of negative contrast microscopy it was found that the surface T-layer of R-variant cell wall was characterized by the tetragonal packaging of protein subunits indicating the regular orientation of phagoreceptors in it. The redistribution of protein subunits in the T-layer of S-variant cell wall prevented from the adsorbance of bacteriophages on the cell surface. The adsorbance of phages on the surface of R-variant cells was observed rather often. It led to the degradation of peptidoglycan, the formation of protoplasts and lysis.

[Growth and spore formation in Bacillus thuringiensis at high substrate concentrations]. / Rost i sporoobrazovanie Bacillus thuringiensis pri vysokikh kontsentratsiiakh substratov.

The work was aimed at studying the effect exerted by elevated concentrations of glucose, yeast extract and acetate on the growth of Bacillus thuringiensis subsp. galleriae, strain 69-6, and on the formation of spores and crystals by it. Glucose concentrations from 30 to 100 g per litre did not prevent spore formation. Yeast extract inhibited spore formation to a greater extent and stopped it almost completely at a concentration of 20 g per litre. Acetate at a concentration of 1.0 to 10 g per litre delayed spore formation and produced a less action on crystal formation, so that those processes were uncoupled in time.

[Growth and development kinetics of Bacillus thuringiensis in batch culture]. / Kinetika rosta i razvitiia Bacillus thuringiensis pri periodicheskom kul'tivirovanii.

The kinetics of Bacillus thuringiensis growth and its assimilation of nutrient substances were studied under the conditions of batch cultivation in a complex medium containing yeast extract and in a chemically defined medium with amino acids. The growth of B. thuringiensis can be divided into five phases: exponential growth; decelerated growth; stationary phase when protein crystals are formed; stationary phase when spores are formed; lysis of sporangia releasing spores. The first phase may in turn be subdivided into three stages according to changes in the specific growth rate and substrate assimilation: a high specific growth rate and no glucose assimilation; an abrupt drop in mu and the beginning of intensive glucose assimilation from the medium; a new rise in the specific growth rate. As follows from the results of studying the kinetics of B. thuringiensis growth in a chemically defined medium, the above changes in the exponential growth phase are due to the fact that the culture assimilates yeast extract components in the complex medium or amino acids in the chemically defined medium during this phase, and then starts to assimilate glucose and ammonium in the following phases of growth.

[Biological characteristics of the variants of Bacillus thuringiensis subsp. galleriae formed during continuous culture]. / O nekotorykh biologicheskikh osobennostiakh variantov Bacillus thuringiensis subsp. galleriae, obrazuiushchikhsia pri nepreryvnom kul'tivirovanii.

Bacillus thuringiensis subsp. galleriae S. variants formed during continuous cultivation differ from the parent culture in certain properties. In contrast to the parent R form, their growth in the chemostat does not yield virulent mutants which can cause their lysis on solid media. The chemostat S forms are resistant against virulent phage mutants produced when the R variants are grown under the conditions of continuous cultivation and against a virulent phage obtained from the parent culture 69-6 under the action of vancomycin. The R forms are sensitive to these phages. When the S forms are grown under the chemostat conditions, they do not revert to the R forms. The R and S forms do not differ noticeably in the character of their growth, formation of spores and crystals, and biological activity.

[Variability of Bacillus thuringiensis under various growth conditions]. / Izmenchivost' Bacillus thuringiensis pri raznykh usloviiakh vyrashchivaniia.

When a lysogenic culture of Bacillus thuringiensis subsp. galleriae 69-6 was grown under the batch conditions, 93-99% of cells in the population produced R-form colonies and ca. 1% yielded S-form colonies. The amount of spore-forming cells was 99% in R-variants and 8% in S-variants. The quantity of S-variants rose abruptly to 99% when the culture was grown under the chemostat conditions. The number of S-variants increased with the rate and the duration of growth. The process was influenced by growth-limiting factors. Temperate phage variants capable of host culture lysis on solid media (i.e. h-mutants) were not found under the conditions of batch cultivation. However, such phage particles (h-mutants) appeared under the conditions of chemostat. The titre of these phage particles reached 10(8), 10(7) and 10(4) particles per 1 ml at limitation with yeast extract, glucose and phosphorus, respectively. Under the conditions of chemostat, the particles behaved as temperate ones and their growth was not found. Irrespective of the limitation, the phage titre did not correlate with the ratio of R and S-forms in the population. When the growth was limited with phosphorus, the quantity of S-forms increased abruptly while the spontaneous induction of the phage was inhibited. The quantity of cells capable of spore formation decreased in the cultures isolated from the chemostat and grown on MPA: 69-80% of the cells in R-forms and merely 8% in S-forms.

[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.

[Effect of temperature and aeration on Bacillus thuringiensis growth and sporulation]. / Vliianie temperatury i aératsii na rost i sporoobrazovanie Bacillus thuringiensis.

The growth of Bacillus thuringiensis was studied as a function of temperature and aeration. The vegetative growth, the yield of viable spores and their thermoresistance did not depend, for all practical purposes, on the rate of aeration within the range of 25 to 60 mg O2 per litre per minute. A rise of temperature from 20 to 35 degrees C doubled the titre of spores and increased their thermoresistance. When the temperature of cultivation was increased to 40 degrees C, the process of spore formation was inhibited.

[Synthetic medium for cultivating Bacillus thuringiensis]. / Sinteticheskaia sreda dlia kul'tivirovaniia Bacillus thuringiensis.

Bacillus thuringiensis subsp. galleriae 69/6 was cultivated in a synthetic medium containing 5 amino acids and nicotinic acid. The dynamics of the culture growth and amino acid assimilation were studied in this medium and in a medium containing yeast extract. The phase of spore germination increased, the yield decreased and the maximal growth rate became higher when the culture grew in the synthetic medium. The percentage of thermoresistant spores was slightly lower in the synthetic medium comparing to the medium with yeast extract.

[Metal content in Bacillus megaterium cells under different cultivation conditions]. / Soderzhanie metallov v kletkakh Bacillus megaterium pri razlichnykh usloviiakh kul'tivirovaniia.

The content of K, Na, Mg, Fe, Al, Ba, Sr and Cu was studied in the cells of a chemostal culture of Bacillus megaterium whose growth was limited with citrate, the growth rates being D=mu=0.2, 0.4 and 0.7 hr(-1). The growth was affected also by acid and alkaline values of pH. The content of metals in the cells could change tenfold, depending on their physiological state. The content of Ca, Mg and Fe increased with the growth rate while that of K remained constant. The content of metals changed even more sharply, depending on pH. In the alkaline medium, the content of K, Na, Mg, Ca and Fe decreased, in contrast to that of Al, Ba, Sr and Cu, probably as a result of damaged transport.

[Chemical composition of cells of a chemostatic culture of Bacillus megaterium during exposure to an alkaline pH value]. / Khimicheskii sostav kletok khemostatnoi kul'tury Bacillus megaterium pri vozdeistvii shchelochnym znacheniem pH.

The culture of Bacillus megaterium was grown under chemostat conditions at a rate of 0.2, 0.4 and 0.7 hr-1, the growth being limited by a low content of citrate, and at alkaline pH values. Critical pH values were obtained for each growth rate: 9.6, 9.2 and 7.6, respectively. The content of protein decreased at alkaline pH, while the synthesis of total lipids, poly-beta-hydroxybutric acid and phospholipids was stimulated. Some changes were found in the ratio between polyphosphates of high molecular weight.

[Physiologo-biochemical properties of a chemostatic culture of Bacillus megaterium at different pH values]. / Fixiologo-biokhimicheskie svoistva khemostatnoi kul'tury Bacillus megaterium pri razlichnykh znacheniiakh pH

Properties of the chemostat culture of Bacillus megaterium were studied during its growth in the state of stress caused by unfavourable acid and alkaline values of pH. The effect of pH is not specific since changes occur in both energy exchange and constructive metabolism. The common action of hydrogen and hydroxyl ions is a decrease in the economic coefficient as greater amounts of the energy substrate are being used, the repression of oxidative enzymes, a decrease in the pool of ATP, and an increase in the respiration quotient. Protein synthesis is inhibited and synthesis of nitrogenless reserve substances is stimulated. Acid and alkaline conditions have also a specific action in the cells of Bac. megaterium. In the alkaline medium, metabolites are liberated into the medium, the cells are enriched with carbohydrates, and acetate is accumulated in the medium. In the acid medium, the cells are enriched with acid insoluble polyphosphates. Idle consumption of the energy substrate takes place.

[Effect of hydrogen ions on the morphology and ultrastructure of Bacillus megaterium]. / Vliianie ionov vodoroda na morfologiiu i ul'trastrukturu Bacillus megaterium

The morphology and ultrastructure of the cells of Bacillus megaterium depend on the concentration of hydrogen ions in the medium which affect, first of all, the function of division. The changes induced by hydrogen ions are temporary and disappear when the cells are put under normal conditions of growth. The "acid-resistant" strain of Bac. megaterium remains viable at a very high concentration of hydrogen ions (pH=4.2) and, though its morphology changes drastically, no essential damages are found, i.e. the cells become adapted to new conditions. The changes are reversible.

[Tolerance to H202 of Mycobacterium carotenum and its carotinoidless mutant]. / Issledovanie ustoichivosti k H202 Mycobacterium carotenum i ego beskarotinoidnogo mutanta

Mycobacterium carotenum is more tolerant to the action of hydrogen peroxide than its white, carotenoidless mutant. This elevated tolerance to H2O2 correlates with a higher content of DNA, RNA, and polysaccharides in the cells; it is not related to the content of proteins and lipids, or to the level of the catalase and peroxidase activity.

[Effect of low pH values on the chemical composition of a chemostat culture of Bacillus megaterium]. / Vliianie nizkogo znacheniia pH na khimicheskii sostav khemostatnoi kul'tury

Inhibition of the growth of Bacillus megaterium was studied in the conditions of chemostat. Inhibition of the growth by hydrogen ions had almost no effect on the content of DNA, RNA, protein and polysaccharides, but the protein-synthesizing activity of RNA changed. The content of polyphosphates, of high and low molecular weight, depended on pH; the relationship was of a non-linear character. The total content of lipids increased with the concentration of hydrogen ions.