[Chemostat cultivation of Candida utilis yeasts under nonstationary temperature conditions]

Abstract

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.