[Properties of the respiratory system of Endomyces magnusii at different stages of development]

The respiration activity and the cytochrome content of the cells of Endomyces magnusii were studied during growth on a medium with 0.6 per cent sucrose. The rate of oxidation, the ration between the activities of respiration and fermentation, the quantitative content and molar ration of cytochromes remained almost the same in the course of growth. Only cytochrome oxidase was involved at the terminal stage of oxidation in the course of growth: the respiration of the cells was inhibited by 90-95 per cent by cyanide, but was resistant to the action of salicyl hydroxamate which was an inhibitor of an alternative pathway of oxidation. Mitochondria from cells harvested at the middle of the logarithmic growth phase almost did not differ in parameters from mitochondria relative to the stationary growth phase: they were tightly coupled and had the theoretical effectiveness of oxidative phosphorylation typical of oxidation of NAD-dependent substrates. All the three points of energy coupling are supposed to function at the earliest phases of growth. Endomyces magnusii differs from other yeasts in following characteristics: the absence of glucose repression, a high constant level of respiration activity, the maximum effectiveness with which the coupling apparatus functions at the earliest phases of growth, and the absence of alternative oxidation pathways.