Metals, minerals and microbes: Geosymbiotic interactions of the Mn cycle
Event details
| Date | 11.10.2011 |
| Hour | 16:15 |
| Speaker | Dr Jasquelin Peña, Institute of Mineralogy and Geochemistry, UNIL |
| Location |
GR C0 01
|
| Category | Conferences - Seminars |
Biogenic manganese oxides (MnO2) are ubiquitous nanoparticulate minerals that contribute to the adsorption of nutrient and toxicant metals, the oxidative degradation of various organic compounds, and the respiration of metal-reducing bacteria in aquatic and terrestrial environments. The formation of these minerals is catalyzed by a diverse and widely-distributed group of bacteria and fungi, often through the enzymatic oxidation of aqueous Mn(II) to Mn(IV). The biogenic Mn(IV) oxide found in field settings, as well as that produced by model bacteria in laboratory culture, is typically a poorly crystalline layer-type hexagonal birnessite enmeshed in an organic matrix of bacterial cells and extracellular polymeric substances. In this talk, I describe the reactivity of various trace metals in preformed and actively-growing Pseudomonas putida-birnessite assemblages. We combined sorption and microbiological experiments with X-ray absorption spectroscopy and first-principles calculations based on density functional theory to elucidate the mechanisms of metal sorption by biogenic MnO2 and to quantify the influence of elevated metal concentrations on bacterial growth, enzymatic MnO2 precipitation, and metal attenuation. This research advances fundamental understanding of metal retention by biogenic MnO2 nanoparticles and highlights the geosymbiotic nature of metal microbe-mineral interactions that regulate the concentrations and distribution of toxicant metals in contaminated ecosystems.
Links
Practical information
- General public
- Free
Contact
- Prof. Tamar Kohn (LCE)