Mycogenic Minerals – Impacts of Multi-Metal Systems on Fungal Mineral Production and Metal Sequestration.

Manganese (Mn) and selenium (Se) are two dynamic, redox sensitive, trace elements that play important roles in human and ecosystem health. In natural systems, Mn oxides can greatly impact the fate and transport of contaminants and nutrients by acting as strong oxidants of organic compounds and redox-sensitive elements, and/or as a sink for contaminants. Selenium, which is both a nutrient and contaminant with a very small window of sufficiency, can undergo microbially mediated aerobic reduction (from aqueous Se(IV or VI) to solid Se(0)) altering its bioavailability. We have identified six fungal species, common to soil and aquatic environments, all of which are capable of individually oxidizing Mn(II) to Mn(III/IV) oxides and aerobically reducing Se(IV or VI) to Se(0). When grown in the presence of both Mn and Se (IV or VI), all fungal species maintain their capacity for reducing Se(IV) to Se(0), and three species (Paraconiothyrium sporulosum, Pyrenochaeta sp., and Stagonospora sp.) simultaneously produce both Mn oxides and Se(0), which are stable in contact with each other. In Se-only experiments, fungi vary in their Se(0) production, from 10-50% Se(0) solid-associated Se produced. We are currenly working to characterize Se and Mn oxide products, including the rates of mineral formation and mineral composition and structure, by each of the fungal species during simultaneous biomineralization as compared to single-element biomineralization processes.