Abstract
Tricarboxylic acid transport systems in Proteus mirabilis IFO 3849, which utilized citric, isocitric, and cis-aconitic acids, were characterized. The results show that P. mirabilis possesses three inducible transport systems for the tricarboxylic acids. The first system is induced by citrate, isocitrate, or cis-aconitate and transports citric and isocitric acids. The affinity of isocitric acid for this system is lower than that of citric acid. The second system, induced by the same acids as in the first system, transports cis-aconitic acid, requires Mg2+ ions, and is stable at pH 8.6 but unstable at pH 7. The third system is induced by citrate and carries citric acid.
