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But siderophores also avidly bind other metals, including toxic ones like lead and cadmium, noted Patricia A. Maurice, a professor of civil engineering and geological sciences at Notre Dame University, in Indiana. At the symposium, Maurice discussed her lab's work on the potential geological consequences of indiscriminate metal binding by bacterially produced siderophores. Previously, Maurice and her coworkers showed that siderophores can release aluminum ions from the aluminum silicate mineral kaolinite. This finding suggests that siderophores may mobilize toxic metals, she said. But siderophores also may adsorb to mineral surfaces, trapping their toxic-metal cargo, Maurice noted. She and graduate student Sarah E. Hepinstall now have found that siderophore-mediated adsorption of metals to kaolinite can in fact occur, but the process is complex and pH-dependent. For instance, certain lead-loaded siderophores--but not others--can enhance adsorption of lead to kaolinite. Maurice and Hepinstall are now using synchroton-based methods to figure out why. Bacteria and other microorganisms also have a hand in weathering of rocks and stones. Some bacteria produce a polysaccharide-based gel that helps them stick to the surface of the rocks that they call home. But depending on the environment and their chemical structure, these bacterially produced polymers can promote dissolution of the rock |
| UPDATE | 10.03 |
| AUTHOR | Notre Dame Uni.'s Maurice Patricia A. |
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