Siderophore production by Proteus mirabilis

Abstract

Studies on the isolation and characterization of P. mirabilis siderophores proved no evidence that these bacteria synthesize catechol- or hydroxamate-type siderophores. Gas chromatography analysis in conjunction with mass spectroscopy revealed the presence of .alpha.-hydroxyisovaleric acid, a previously unknown metabolite. Additional substantiating evidence for the presence of .alpha.-hydroxyisovaleric acid in these bacteria was obtained from experiments involving the use of TLC and a UV absorption spectrum. This compound is capable of removing Fe from the synthetic chelator, ethylene-diamine-di-orthohydroxyphenyl acetic acid and supplying that Fe to the bacteria in a solid agar medium and in a liquid medium. P. mirabilis possessed an enzyme capable of catalyzing the reaction by which .alpha.-hydroxyisovaleric acid is converted to .alpha.-ketoisovaleric acid, an intermediate in the valine biosynthetic pathway.