Production of 5-Methlthioribose by 'Escherichia coli.'

A study of sulfur metabolism in micro-organisms led to the isolation and identification of 5-methylthioribose (MTR) from E. coli B. MTR labeled with 35S was excreted by the bacterium during incubation in glucose-salts medium supplemented with 35SO4(-2). It was isolated by ethanol extraction of the lyophilized incubation medium and chromatography. Accumulation of MTR in the culture medium was independent of inoculum size and time of 35SO4(-2) addition. It was dependent on sulfate concentration, which limited the cell population attained and on time of incubation. High cell populations and incubation for 3 days made MTR the major sulfur-containing, ethanol-soluble product in the medium. Production continued after maximum cell density was attained, but extended incubation led to cell lysis and a decrease in MTR. Never abundant there, it declined inside the cells with incubation time. MTR was produced in similar amounts by E. coli in media limited (35 micromoles) and not limited (1.6 micromoles in SO4(-2). Therefore, it is a normal metabolite. (Author)