[Transport and accumulation of biotin by cells of various fungal and yeast strains].

Transport of 14C-biotin was studied in cells of different biotin-prototrophous yeast and mold fungal strains. An inverse correlation was established between the capability of the fungi to synthesize biotin and the exogenous vitamin transport: 14C-biotin did not penetrate into the cells of strains which excreted great quantities of the vitamin. It is likely that a higher level of biotin synthesis in certain fungi is caused by a peculiar transport system, which results in a one-way permeability of their cell membrane for biotin. Biotin is eliminated from the cell and cannot repress its own synthesis. Active transport of biotin in the studied prototrophous organisms occurs against a concentration gradient and does not depend on the presence of glucose in the medium. There are apparently other energy sources for this process.