Siderophores are a diverse group of low molecular weight biogenic metallophores with a particular affinity for Fe(III) but they also have potential to complex a number of other polyvalent metal cations, including Cr(III). Here we show that two hydroxamate siderophores, desferrioxamine B and rhodotorulic acid, at environmentally relevant concentrations, facilitate the dissolution of hydroxy-Cr(III) precipitates from a common layer silicate. Desferrioxamine B and rhodotorulic acid induced maximum initial Cr dissolution rates of 11.3 +/- 1.7 x 10(- 4) and 9.03 +/- 0.68 x 10(- 4) A mu mol m(- 2) h(- 1), respectively, yielding maximum solution Cr concentrations of 0.26 +/- 0.01 and 0.20 +/- 0.02 A mu mol m(- 2), respectively. These data demonstrate that hydroxamate siderophores may play an important role increasing the dispersal of Cr in natural environments, thus facilitating greater bioavailability of this potential toxin.
