Growth of Pseudomonas mendocina on Fe(III) (hydr)Oxides

Although iron (Fe) is an essential element for almost all living organisms, little is known regarding its acquisition from the insoluble Fe(III) (hydr )oxides in aerobic environments. In this study a strict aerobe, Pseudomonas mendocina, was grown in batch culture with hematite, goethite, or ferrihyd rite as a source of Fe. P. mendocina obtained Fe from these minerals in the following order: goethite > hematite > ferrihydrite. Furthermore, Fe relea se from each of the minerals appears to have occurred in excess, as evidenc ed by the growth of P. mendocina in the medium above that of the insoluble Fe(III) (hydr)oxide aggregates, and this release was independent of the min eral's surface area. These results demonstrate that an aerobic microorganis m was able to obtain Fe for growth from several insoluble Fe minerals and d id so with various growth rates.