CBE Research Area:
Bioelectrochemistry
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Figure represents pits initiated in 316L stainless steel by
Leptothrix discophora treated with ennoblement by manganese biomineralization and a 0.2M sodium chloride solution. Pit is 50nm deep and 10 micron long by 1 micron wide, the same dimensions as the bacteria. |
The Bioelectrochemistry Research Area studies interactions between microorganisms, minerals, and metals including extracellular, intracellular, and cell-surface interactions. Processes studied are: biological oxidation and reduction of minerals and metals, biological accumulation of minerals and metals,
and biological precipitation/dissolution of minerals and metals. Areas of application are: bioremediation, bioleaching, biohydrometallurgy, and Microbially Influenced
Corrosion (MIC).
Initially, the new Research Area is targeting MIC. Most MIC studies reduce the scope of interest to the single pragmatic question: How does the presence of microorganisms influence the corrosion rate and/or corrosion mechanism under a given set of conditions? We think that a new, more fundamental approach to metal–microbe interactions will enhance the progress in understanding the electrochemical consequences of microbial colonization of metal surfaces. This would be an approach where (bio)corrosion constitutes a subset of problems, instead of being the central issue. We believe that investigating "biomineralization" processes occurring on metal surfaces will provide a better point of departure to study MIC.
It is well known that minerals can accumulate on metal surfaces, corrosion products, passive oxide layers, and materials precipitated from solution. Ideally, these minerals are in thermodynamic equilibrium with the relevant dissolved species. The presence of microorganisms, however, modifies deposition and dissolution rates of these minerals, and by this mechanism influences the electrochemical properties of the metals or alloys. The novelty of our approach is in the conceptual treatment of the mineral phase deposited on metal surfaces. From our point of view, materials precipitated from solution and the corrosion products all appear in this model as one phase of the
system: "the minerals". Fundamental assumptions of our approach are:
1) metal ion oxidation and reduction reactions play a significant role in microbial energetics/physiology, and impact directly on microbial ecology, and
2) solubilization/precipitation of minerals at metal surfaces both influence the availability of metal ions to microbial redox reactions and
give rise to major physicochemical effects on the system as a whole.
For more information, write to
Dr. Zbigniew Lewandowski. |
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