[Biotin transport in the yeast Trichosporon cutaneum]

Biotin transport was studied in the yeast Trichosporon cutaneum and was shown to be the active transport with Km = 1.5 X 10(-7) M. The process depended on the pH and temperature whose optimal values were pH 6.8-7.2 and 35-40 degrees C. T. cutaneum biotin permease was highly specific for biotin and was inhibited by biotin analogs. Biotin uptake by the cells was inhibited by glucose. Excess biotin in the growth medium caused partial repression of its transport system in the yeast. Synthesis of biotin permease by T. cutaneum depended on the nature of a catabolite present in the growth medium. The rate of biotin transport was highest in the cells grown in the presence of ramnose or arabinose and lowest in the cells utilizing galactose, lactose or xylose.