The metabolism of [¹⁴C]bicarbonate byStreptococcus lactis: the synthesis of succinic acid

Whole cells of Streptococcus lactis C10, when incubated with an energy source, converted fumarate to succinate and malate to lactate. Cell-free extracts of Str. lactis C10 contained fumarate reductase, but no aspartase, adenylosuccinate synthetase and lyase or argininosuccinate synthetase and lyase activity could be detected. Cells grown in the presence of [14C]bicarbonate produced labelled succinate during the synthesis of purine bases. However, the amount of succinate produced by this pathway only accounted for approximately one-sixth of the succinate produced by the cells.