Thermotolerant Candida blankii Yeast Strain: Biochemical Properties with a Special Reference to Bioenergetics
Elena Isakova*, Andrei Belov, Ludmila Gorpenko, Renata Zvyagilskaya
Bach Institute of Biochemistry, Russian Academy of Sciences, Leninsky pr. 33, 117071 Moscow, Russia
Article history:
Received July 28, 1997
Accepted January 7, 1998
Key words:
yeast, termotolerant, thermophilic, energy metabolizam, mitochondria
Summary:
Candida blankii cells readily utilized both fermentable and nonfermentable substrates at 30-45 °C, with the upper temperature limits being at 43-45 "C. No considerable growth was obseived at 20-24 °C. The respiratory pattern in cells grown on glucose, succinate or soluble paraffins was almost the same: respiratory rales reached their maxima at the exponential groioth phase; exponentially growing cells displayed only the cytochrome oxidative pathway; in cells harvested at the stationary growth phase, both the cytochrome and alternative pathways coexisted. When C. blankii cells were grown on soluble paraffins, succinate or low (derepressible) concentrations of glucose, the oxidative phosphorylation system predominated in the energy budget of the cell. Moreover, the higher temperature of growth (in the range of 30-43 °C) - the greater engagement of the oxidative phosphorylation system occurred. Mitochondria isolated from cells grown at 43 °C on sucrose or succinate possessed the respiratory chain with all three points of energy conservation. Thus, some important regularities providing heller understanding of mechanissm underlying growth of lower eukariotes at high permissible temperatures were revealed. It is becoming evident thai 43-45 °C is still the temperature regime at which the respiratory chain functioning is not restricted possibly by balanced changes in the barrier properties of the inner mitochondrial membrane.
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