DETECTION OF SIDEROPHORES IN NATURAL ENVIRONMENTS

Siderophores are biogenic chelating agents that are exuded by microbes and plants to facilitate the solubilization and uptake of trace nutrient metals. These molecules thus forge a direct linkage between organisms and the solid phase components of soils, sediments, and aqueous environments. Despite their biological and geochemical importance, many barriers exist to the study of siderophores in the environment. Siderophores are operationally defined and structurally diverse, with over 500 different siderophore structures currently known. In addition, they are thought to occur in low concentrations, which may vary significantly over short spatial distances and time periods. To overcome these barriers, a more rapid, generalized assay is required to assess the effective concentrations of siderophores and related chelating agents in the environment. In this presentation, we summarize our efforts to utilize the chrome azurol S (CAS) assay to quantify siderophores at nanomolar concentrations. The results are discussed in terms of the detection of free siderophores in natural waters, and future applicability to the soil environment.