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Biomedical subjects

I N Pozmogova

Publications and source records attributed to I N Pozmogova.

At least 19 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↗