[Chemostat cultivation of Candida utilis yeasts under nonstationary temperature conditions]. / Khemostatnoe kul'tivirovanie drozhzhei Candida utilis pri nestatsionarnykh temperaturnykh usloviiakh.

The yeast Candida utilis VKMY-1668 was cultivated in the chemostat (D = 0,34 h-1) while the temperature was changed many times from 31 to 37 degrees C at a frequency of 2 h (one generation). Control experiments were conducted at the constant optimal (31 degrees C) or supraoptimal (37 degrees C) temperatures. Changes in the biochemical composition and morphology of the yeast were assayed as well as electro-kinetic characteristics of the cell surface. All of the above properties changed periodically with a change in the growth temperature. This occurred however only at the first stage of the nonstationary temperature regime. Later, changes in the temperature from 31 to 37 degrees C had no effect on the content of RNA, protein and amino acids in the biomass or on the electro-kinetic characteristics of the cells. Apparently, the nonstationary temperature regime was responsible for stationary chemostat cultivation, similar to the growth at the constant optimal temperature of 31 degrees C (despite changes in the temperature from 31 to 37 degrees C). Protein content in the yeast was the most stable parameter while RNA content changed in the biomass in the course of growth.

[Effect of heat shock on the amino acid makeup of the whole cells and walls of Candida utilis yeasts in chemostat cultivation]. / Vliianie teplovogo shoka na aminokislotnyi sostav tselykh kletok i stenok drozhzhei Candida utilis pri khemostatnom kul'tivirovanii.

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.