Unraveling Cellular Controls on the Diversity of Mn Oxides Formed By Fungi
EMSL Project ID
40062
Abstract
Mn(III/IV) oxides are potent scavengers and oxidants of numerous nutrients and contaminants within the environment. The oxidation and sorption capacity of Mn oxide phases, however, is highly dependent upon their size, composition, and structure. The formation of Mn oxides is catalyzed by a diverse group of bacteria and fungi, which occurs via a number of direct (enzymatic) and indirect (metabolite) Mn(II) oxidative pathways. Fungi, in particular, have a number of oxidative pathways associated with different cellular structures (e.g., spores, hyphae) and growth stages. Very little is known, however, about either the oxidation processes utilized by fungi or the structures and reactivity of the resulting mineral products. We recently isolated and identified 13 phylogenetically distinct species of Mn(II)-oxidizing fungi from an industrially impacted freshwater pond and several acid mine drainage treatment systems. These organisms provide an ideal opportunity to define the diversity (in terms of structure, size, and speciation) of biogenic Mn oxides formed as a function of species and growth state. We are currently investigating the bulk composition, degree of site vacancies, and stacking order of the Mn oxide phases using X-ray absorption spectroscopy (XAS). Here we propose to couple the XAS results with high-resolution transmission electron microscopy (TEM), selected area electron diffraction (SAED), and microbeam X-ray diffraction (XRD) for a spatially-resolved examination of the size, morphology, and structure of precipitates with respect to species and location (e.g., associated with hyphae, spores, or fruiting-bodies). Together, this information will reveal how cellular relationships impact the diversity of Mn oxide species and structures associated with fungi, which will ultimately illustrate the impact that fungi have on the reactivity of surface environments. This proposal for access to EMSL's high resolution, Cryo-TEM, and Microbeam XRD for 120 hours is an extension of a prior initial rapid access proposal in which we successfully tested the feasibility of, and developed the protocols for, examining the cellular-precipitate interactions.
Project Details
Project type
Large-Scale EMSL Research
Start Date
2010-10-01
End Date
2013-09-30
Status
Closed
Released Data Link
Team
Principal Investigator
Team Members
Related Publications
Hansel CM, CA Zeiner, CM Santelli, and SM Webb. 2012. "Mn(II) Oxidation by an Ascomycete Fungus is Linked to Superoxide Production During Asexual Reproduction." Proceedings of the National Academy of Sciences of the United States of America 109(31):12621-12625. doi:10.1073/pnas.1203885109
Santelli CM, SM Webb, A Dohnalkova, and CM Hansel. 2011. "Diversity of Mn oxides produced by Mn(II)-oxidizing fungi." Geochimica et Cosmochimica Acta 75(10):2762-2776. doi:10.1016/j.gca.2011.02.022