[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.

[Yeast growth under alternating temperature conditions and the possibility of originating thermotolerant forms]. / Rost drozhzhei v usloviiakh peremennykh temperatur i vozmozhnost' proiskhozhdeniia termotolerantnykh form.

The chemostat culture of Candida utilis was grown under the conditions of varying temperatures: one generation grew at an optimal temperature of 31 degrees C, the second at supraoptimal temperatures: either 35, 36 or 37 degrees C; these were alternated during 6-8 generations. Changes in the growth yield were studied as well as changes in the content of protein, RNA and DNA in cells and changes in the zeta-potential of cells at a growth rate of 0.34 hr-1. At this rate, the population became "synchronous-like" and contained up to 60% of simultaneously budding cells. When the temperature of cultivation was periodically changed, the content of RNA and DNA in the biomass fluctuated at a decreasing amplitude around values found during the growth at the optimal temperature; the electro-kinetic characteristics of cells were also in the attenuated oscillating state approaching the norm. The authors discuss how the population retains the value of growth yield constant when it is grown under the conditions of varying temperatures and what is the origin of thermotolerant forms.

[Electrokinetic properties of microorganisms as dependent on culture conditions]. / Elektrokineticheskie svoistva mikroorganizmov v zavisimosti ot uslovii kul'tivirovaniia.

The electrokinetic properties of cells were studied with the batch and continuous cultures of Bacillus megaterium and the chemostat culture of Candida utilis. The above cells growing at a higher rate had a higher electrophoretic mobility and a greater negative zeta potential; this seems to stem from the accumulation of negatively charged groups on their surface. The bacterial cells had higher values of electrophoretic mobility and electrokinetic potential comparing to the yeast cells; the electrokinetic properties of the bacterial cells changed more with a variation of the growth rate than in the yeast cells.