Non-Utilization of sucrose by the petite mutant of a distiller's yeast

T-2 toxin inhibits mitochondrial function in yeast

T-2 toxin inhibits oxygen consumption of whole cells and purified mitochondria of Saccharomyces cerevisiae. Inhibition of mitochondrial respiration is not relieved by 2, 4-dinitrophenol, indicating that T-2 toxin inhibits mitochondrial function at the level of the electron transport chain. T-2 toxin inhibition of state 3 respiration (with succinate) is overcome by N, N, N', N'-tetramethyl-p-phenylenediamine, indicating inhibition of site II of the electron transport chain. T-2 toxin inhibits mitochondrial succinate dehydrogenase activity and increases mitochondrial NADH dehydrogenase activity.

Impairment of insulin assimilation and beta-fructosidase activity due to a petite mutation in Kluyveromyces marxianus

A respiratory deficient mutant of Kluyveromyces fragilis was isolated using ethidium bromide mutagenesis. It was characterized by a loss of cytochromes a + a3 and deficiency in cytochrome b. This petite mutant has brought about modifications in the excretion pattern of beta-fructosidase active on saccharose and inulin. The mutant practically no longer excretes the enzyme, and is incapable of growth and fermentation in the presence of inulin. The study of the activities of different enzyme extracts (culture medium, whole and disrupted cells) on inulin and saccharose suggests the existence of an unique enzyme system capable of taking several forms, and also shows the influence of the growth substrate on the I/S activity ratio.