Mitochondrial Activities in the Methylotrophic Yeast Kloeckera sp. 2201 During Growth with Glucose and/or Methanol

Abstract

The methylotrophic yeast Kloeckera sp. 2201 was grown in carbon-limited chemostat cultures with glucose and/or methanol as the carbon sources, to investigate the regulation of the synthesis of enzymes involved in the tricarboxylic acid (TCA) cycle and the electron transport chain. Except for malate dehydrogenase, enzymes of the TCA cycle were repressed during growth with methanol to specific activities of 20-40% of those found in cells growing under identical growth conditions but with glucose as the carbon source. In methanol-grown cells, the specific activities of the enzymes of the respiratory chain were also repressed compared to cells grown with glucose [60-70% for NADH:cytochrome c (cyt c) oxidoreductase and cyt c oxidase; approximately 40 % for succinate : cyt c oxidoreductase]. The measurement of cytochrome oxidized-minus-reduced spectra was impossible in methanol-grown cells because of interference of the chromophoric group of the peroxisomal enzyme alcohol oxidase under these growth conditions. The relative cytochrome c content of mitochondria from methanol-grown cells, separated from peroxisomes by density gradient centrifugation, was significantly lower (cyt aa3 : cyt b : cyt c = 1 : 1.24 : 0436) than in mitochondria from glucose-grown cells (cyt aa3 : cyt b : cyt c = 1 : 1-27 : 2-20). The results are discussed with respect to the generation of energy for biosynthesis during growth with glucose and/or methanol.

Kinetics and physiological implications of the growth behaviour of Eubacterium limosum on glucose/methanol mixtures

“…Alternatively, simultaneous use may take place under conditions in which the substrates are present at only low concentrations ; conditions often encountered in natural habitats and relatively simple to model using a chemostat. Various authors have employed continuous cultures to study microbial behaviour on various substrate mixtures and growth rates (Brooke & Attwood, 1983;Egli et al, 1980Egli et al, , 1983Egli & Lindley, 1984 The following consequences af mixed substrate growth have been reported.…”