Some specific features of the respiration of hydrocarbon-utilizable Candida yeasts

The respiration of both glucose-grown and hydrocarbon-grown cells of Candida tropicalis pK 233 harvested in the stationary phases was not inhibited by cyanide when glucose was used as oxidation substrate, but the former was rather stimulated in the presence of cyanide. When n-alkanes were used as oxidation substrate, cyanide lowered the respiratory activities of both cells to about 50%. With respect to the susceptibility to cyanide, the younger cells growing on n-alkanes were less sensitive in hydrocarbon oxidizing ability than the older cells, whereas the older cells growing on glucose or n-alkanes were more resistant in glucose oxidizing ability than the younger cells. Acetate was oxidized by both glucose-grown and hydrocarbon-grown cells of the yeast. Laurate was oxidized by hydrocarbon-grown cells, but not by glucose-grown cells. The respiration on laurate was inhibited completely by 3.3 mM of cyanide. In general, hydrocarbon-grown cells of Candida tropicalis pK 233 were more sensitive to various respiratory inhibitors than glucose-grown cells, although the oxidation substrates had a significant effect. The respiration of both glucose-grown and hydrocarbon-grown cells of C. albicans, C. guilliermondii and C. lipolytica harvested in the stationary phases was also resistant to cyanide when glucose was used as oxidation substrate. But the respiration on n-alkanes of these cells was inhibited significantly by 3.3 mM of cyanide except for C. albicans.