While many metals are essential trace nutrients for life, at high concentrations these same metals can be toxic and at times fatal. Within acidic mine waters from abandoned coal mines, concentrations of the metal manganese (Mn) can be two orders of magnitude higher than levels considered a health risk for neurological disorders. We have recently found that oxidation and subsequent immobilization of Mn in acid mine drainage (AMD) environments is mediated by an abundant fungal community that completely and rapidly oxidizes Mn(II) to Mn(III/IV) oxides. Although fungal mediated processes are universally observed and their impact on geological processes indisputable, little is known about the fungal species involved in the biogeochemical cycles of metals, the mechanisms that are employed, and their impact on the mineralogical framework and reactivity of soils and sediments. This CAREER proposal presents an integrated education and research plan to explore and ultimately define the importance of fungi in the oxidation of Mn(II) within surface environments, in particular those impacted by acidic mine waters. The research will be conducted in the scope of an undergraduate project on fungal diversity and a graduate student thesis on the enzymatic, physiological, and geochemical controls on Mn(II) oxidation and biomineralization by key Mn(II)-oxidizing fungal isolates. The specific objectives are to define (1) the phylogenetic and ecological diversity of Mn(II)-oxidizing fungi in AMD systems, (2) the fungal mediated (a)biotic Mn(II) oxidative pathways, (3) the role of biological clocks on Mn(II) oxidation, and (4) the Mn(II) oxidation rates and solid-phase. This research will involve a multidisciplinary approach coupling molecular biology, enzymatic and chemical assays, microscopy and sophisticated micro-spectroscopic techniques to probe microbe-metal-mineral interactions at the molecular and bulk scale. The research outlined in this CAREER proposal will fill major gaps in our knowledge of the biological and geochemical controls of the Mn cycle ? information that is of crucial importance for improving in situ bioremediation (e.g. AMD treatment), stimulating primary productivity, and predicting the fate and transport of contaminants in the environment. Broader Impacts: In most circumstances, placing abstract chemical and biological concepts into real-life situations and applications can peak students interest and learning. The visually striking and disturbing devastation caused by AMD is an ideal environmental framework to educate students about the complexity of physical, microbiological, and chemical processes that govern the health of the natural world. The main educational outreach component of this proposal will be the creation and instruction of an annual five-day professional development workshop on AMD microbiology for informal and formal educators. The workshop, co-hosted by the Microbial Sciences Initiative at Harvard and the Jennings Environmental Education Center (JEEC), is entitled ?Living in the Acid: The Microbes that Create and Remediate Acid Mine Drainage? and will focus on the biogeochemistry and microbial ecology of AMD ecosystems, including lectures, lab and field exercises, and curriculum development forums. This workshop will be a unique experiential learning opportunity for educators seeking hands-on science instruction with microbes, environmental quality, and the cutting-edge concept of bioremediation. New findings from our proposed research will be directly integrated into the workshop and provide information, including high-resolution images, for permanent public displays for the JEEC. This workshop will serve as a conduit to educate a wide socioeconomic diversity of students spanning from rural to urban settings and to channel advances in our understanding of environmental microbiology and bioremediation to the classroom and to the general public.