Microorganisms “Breathe” Humic Particulates


Organic matter in the soil, such as humic substances, plays a key role in determining the fate and transport of radioactive and heavy metal contaminants in the subsurface. Just-published research has demonstrated for the first time that particulate humic substances can serve as electron carriers for anaerobic metabolism by microorganisms. The humic substances act to shuttle electrons between the microorganisms and iron oxide minerals. Recent reports have suggested that microbial communities in sedimentary environments may be networked via nanowires or other bacterial appendages (or secretions) capable of accepting and donating electrons derived from microbial metabolism. Thus, these redox active humic particulates, in coordination with appropriate mineral phases, could be an integral component of these microbial networks, and have a significant role in determining the chemical form – and the resulting mobility – of contaminants of interest to DOE. The research is published in the June 2010 issue of Nature Geoscience. It was conducted by DOE-funded scientists at the University of Wisconsin, Madison, and at laboratories in Germany.


E.E. Roden, A. Kappler, I. Bauer, J. Jiang, A. Paul, R. Stoesser, H. Konishi, H. Xu, (2010), Nature Geoscience, 3:417-421.