IRON ACQUISITION FROM HYDROUS FE(III)-OXIDES BY AN AEROBIC PSEUDOMONAS SP

Iron is a metabolic requirement of living systems, yet iron is very in soluble in aerobic, neutral environments. Therefore, the amount of iro n in solution under these conditions is not sufficient to meet the nut rient requirements of microorganisms. It has been assumed that microor ganisms acquire iron in these environments through the use of specific iron chelating compounds called siderophores. Interestingly, there is little quantitative data in the literature to support this hypothesis . Our studies were initiated to investigate the mechanism(s) used by a n aerobic microorganism to acquire iron from a relatively insoluble ir on oxide. When iron was supplied in the form of hematite, a Pseudomona s sp. was able to achieve moderate growth, as compared to growth on Fe EDTA. Analysis using high-performance liquid chromatography (HPLC) of the metabolic products of this species showed significant differences between growth on hematite as compared to FeEDTA. The results of these experiments will be discussed in terms of our current knowledge of mi crobial enhanced iron dissolution, and compared to abiotic dissolution rates.