Transport of B-Vitamins in Microorganisms. III. Chromatographic Studies on the Radioactivity Extracted from Non-proliferating Cells of Lactobacillus fermenti after Exposure to Labelled Thiamine.

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Abstract
Chromatographic studies were carried out on extracts from thiamine deficient non-proliferating cells of L. fermenti after short exposure of the cells to C14-thiamine in the presence of glucose, Mg2+, various buffers, and certain other additions. The chromatograms were evaluated quantitatively and the relationship between the proportion of free thiamine and the total uptake was studied using different kinds of cells. It was found that most of the labelled thiamine is rapidy converted to a phosphorylated derivative (presumably thiamine pyrophosphate). The extent of this conversion is considerably decreased, however, under conditions limiting the phosphorylation of thiamine without a simultaneous decrease of the total uptake. In extracts from severely phosphate depleted cells the proportion of free thiamine was about 70% of the total radioactivity. Estimations of the intracellular concentrations of free thiamine indicated accumulation of the vitamin against considerable concentration gradients.