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I N Pozmogova

Publications and source records attributed to I N Pozmogova.

18 recordsLinked to original sources
PubMedDate not supplied

[ATP content in Candida tropicalis cells growing at different temperatures].

The thermotolerant yeast Candida tropicalis, strain T-20, was cultivated on a chemically defined medium with glucose or malt wort in flasks with shaking at three temperatures: optimal (36degreesC), supraoptimal (38degreesC) and submaximal (41degreesC). An increase of temperature within these limits caused an increase in ATP content in yeast cells and a decrease in phosphohydrolase (ATPase) activity.

Adenosine Triphosphatases↗
PubMedDate not supplied

[Effect of heat shock on the amino acid makeup of the whole cells and walls of Candida utilis yeasts in chemostat cultivation].

The amino acid composition of intact cells and cell walls was determined in Candida utilis AUCMY-1,668 growing in the regime of chemostat with limitation by glycerol or ethanol deficiency at a temperature of 30 degrees C (control) or with inhibition by an elevated temperature of 40 degrees C (experiment). In the control, intact cells contained 43-44% of amino acids, and cell walls, about 10% (per the weight of dry cell walls); the following amino acids prevailed in the cell walls: threonine, glutamic acid, serine and leucine. The content of amino acids decreased in both the intact cells and cell walls at the elevated temperature (40 degrees C). The content of leucine, methionine, tyrosine and cystine decreased in the cell walls more than in the intact cells (with regard to the total amino acid content of the cell walls and intact cells, respectively). Under the action of the elevated temperature, the cells became larger and did not separate: the scar formed at the end of budding stretched between the mother and daughter cells holding them together.

Amino Acids↗
PubMedDate not supplied

[Effect of raised temperatures on the protein and RNA synthesis rate in yeasts].

The rates of incorporation of labelled precursors of protein (14C-DL-leucine) and RNA (14C-uracil) into the cells of synchronous yeast cultures of Pichia membranaefaciens, Hansenula anomala, Saccharomyces cerevisiae and Saccharomyces (fabospora) fragilis were studied at different temperatures. Synthesis of RNA and then of protein was inhibited in H. anomala if the temperature was increased above the optimal one. This is manifested even more distinctly in Sacch. cerevisiae and P. membranaefaciens. In the thermotolerant yeast Sacch. fragilis, the incorporation of 14C-uracil was inhibited at temperatures above 40 degrees C while the rate of protein synthesis did not decrease.

Culture Media↗
PubMedDate not supplied

[Principle growth indices of a chemostat Candida utilis culture resistant to acid pH values].

The kinetics of growth of the Candida utilis chemostat culture 1668-3-37 was studied in a synthetic medium with ethanol at different values of pH and temperature. Chemostat curves were obtained for the pH of the medium of 4.5 and 3.0 and the temperature of 32 degrees C. The following growth characteristics were determined: the maximal growth rate (mumax), the economical coefficient (Y), the substrate (saturation) constant (Ks), the rate of ethanol uptake (q), maintenance energy (m). The minimal amount of ethanol inhibiting the yeast growth was assayed in short-term experiments under periodic conditions with shaking. The value of mumax was 0.35 hr-1 when the yeast was cultivated at 32 degrees C and the pH 4.5, and 0.32 hr-1 at the pH 3.0. The value of Ks varied by an order of magnitude at different pH values when the chemostat culture was grown at D=0.2 hr-1: 36.0 mg/litre at the pH of 3.0 and 3.75 mg/litre at the pH of 4.5. The value of m was close to 0 at the pH of 4.5 and equaled 5--7 mg of ethanol per gram of dry biomass per hour at the pH of 3.0; it was still higher when the temperature of cultivation was increased to 38 degrees C. The minimal substrate (ethanol) concentration inhibiting the yeast growth was constant at different cultivation conditions (pH 3.0 or 4.5 and temperature 32 or 38 degrees C), being equal to 0.45% (v/v) of ethanol.

Candida↗
PubMedDate not supplied

[Cell adhesion in a chemostat culture of Candida utilis under the influence of supraoptimal temperature and elevated acidity].

The effect of the supraoptimal temperature (38, 40 degrees C) on the chemostat culture of Candida utilis was studied. The above factor caused a part of the biomass to float as a thin layer of foam to the surface of the medium. After an hour, the concentration of the cells on the surface could be four times as high as that within the medium. The content of protein was the same in the cells taken from the surface and from the depth. Singular cells or their groups (2 or 4--8 cells) were found deep in the medium whereas cells on the surface were aggregated forming conglomerates of 20--100 and more cells. The simultaneous action of the elevated tmperature and the acid pH value made flotation of cells onto the surface more stable and protracted (it could be maintained in a chemostat for weeks).

Candida↗
PubMedDate not supplied

[Several parameters of the growth of chemostatic culture of Candida utilis in the presence of optimal and submaximal temperatures].

Candida utilis BKM Y-1668 was cultivated in the chemostat (limitation with glycerol) with the rate of flow D from 0.05 to 0.3 hr-1; the economic coefficient Y and Ks were constant at the optimum temperature of growth (30 degrees C). The maximum growth rate was 0.35 hr-1. The content of ATP in the cells and the energy charge of the cell decreased, and the content of ADP and AMP and the activity of phoshohydrolases increased in the cell, with an increase in D from 0.05 to 0.3 hr-1. Small amounts of glycerol and phosphorus were expended for maintaining life without multiplication (m) at 30 degrees C. At the submaximum temperature (40 degrees C), growth of the cells was inhibited, the rate of assimilation of glycerol and phosphorus, and m, increased. The content of ATP in the cells and their energy charge also increased.

Adenosine Triphosphate↗
PubMedDate not supplied

[Effect of elevated temperature on the morphology of a chemostat culture of Candida utilis yeasts and on their content of nucleic acids].

The effect of elevated temperature (40 degrees C) on a chemostat culture of Candida utilis was studied at different rates of dilution, D = 0.1 and 0.3 hr-1. The cells in the fermenter being in the stationary state at the optimum temperature of 30 degrees C were gradually washed-out 5 hours after the action of this temperature, and the population consisted of non-divided cells. In the majority of such "double" cells, the nucleus was contained in both the parent and the daughter parts. The content of RNA decreased by 31%, that of DNA, by 20%, and that of protein, by 13% (per 1 mg of biomass).

Candida↗
PubMedDate not supplied

[Effect of raised temperature on the developmental cycle of Candida utilis yeasts].

The effect of the submaximal temperature (41.5 degrees C) on growth was studied with a synchronous periodic yeast culture. If the cells were subjected to the action of elevated temperature at the beginning of the growth cycle, the formation of buds was not inhibited in contrast to the separation of nuclei between the daughter and parent cells. If the cells started their growth cycle at the optimal temperature of 32 degrees C and, after spending 0.6 of the cycle at this temperature, were subjected to a temperature of 41.5 degrees C, the separation of nuclei between the daughter and parent cells took place, but the cells were not entirely separated one from another.

Candida↗
PubMedDate not supplied

[Effect of increased temperatures on RNA and protein synthesis in the cells of a synchronous Candida utilis culture].

The rate of incorporation of labeled precursors for RNA ([14C]uracil) and protein ([14C]DL-leucine) into the cells of the synchronous culture of Candida utilis VKMY-1668 (the optimum temperature of growth, 31--32 degrees C) was studied as a function of different temperatures (28, 31, 32, 34, 36, 38, and 41 decrees C). The yeast was grown on a simple mineral medium containing glycerol. RNA synthesis was found to be more susceptible to elevated temperature than protein synthesis: the maximum rate of incorporation was registered at 32--34 degrees C for [14C]DL-leucine and only at 32 degrees C for [14C]uracil (the rate of its incorporation at 34 degrees C decreased by 50% as compared to that at 32 degrees C). The rate of incorporation of [14C]uracil at 34 degrees C reached 100% (the rate at 32 degrees C) when yeast autolysate was added to the medium, and 75 and 70%, respectively, upon the addition of DL-methionine or Mg2+ (as compared to 50% without them).

Candida↗
PubMedDate not supplied

[Metabolic characteristics of thermophilic microorganisms].

The maximum growth rate of thermophilic bacteria was found in the exponential growth phase during 2 to 3 hours, and the metabolism was aerobic. In the linear growth phase, the substrate (glucose) was metabolized both by the aerobic and anaerobic pathways during the cultivation of the thermophilic bacteria with shaking; this was confirmed by increasing values of the respiratory quotient and by the evolution of volatile acids. The mesophilic bacteria oxidized the substrate by the aerobic pathway under the same conditions of cultivation, both during the exponential and linear growth phases, and had the stable value of the respiratory quotient. The economic coefficient was lower in the thermophilic microorganisms (bacteria and thermotolerant yeasts) than in the mesophilic cultures.

Aerobiosis↗
PubMedDate not supplied

[Dynamics of growth of mesophilic and thermophilic microflora from hot springs].

Samples containing mesophilic and thermophilic bacteria from a natural thermal spring were inoculated into a medium made with the water of the same spring. The growth rate of the thermophilic microflora was higher but the mesophilic microflora produced more biomass than the thermophilic bacteria.

Bacillus megaterium↗
PubMedDate not supplied

[The physiology of thermophilic and mesophilic bacilli during development at optimal and submaximal temperatures].

Thermophilic bacilli, contrary to mesophilic, grow equally well under aerobic and anaerobic conditions. This may be due to the presence of more active anaerobic dehydrogenases in thermophilic organisms. The activity of glucose-6-phosphate dehydrogenase and alcohol dehydrogenase, and the content of ATP, increased in the cells of thermophilic Bac. stearothermophilus 159 and mesophilic Bac. megaterium M strains growing at temperatures close to maximal. The activity of glutamate dehydrogenase under these conditions was inhibited.

Adenosine Triphosphate↗