U.S. Department of Energy Office of Biological and Environmental Research

BER Research Highlights

Microbes Use Tiny Magnets as Batteries
Published: March 27, 2015
Posted: November 23, 2015

In the subsurface environment, below the water level, iron-oxidizing bacteria strip electrons from the naturally occurring battery (left); the reducing bacteria, which are active at night, add electrons, effectively recharging the battery (right). [Image courtesy University of Tuebingen]

Understanding subsurface electron flow is vital in understanding elemental cycling and remediating subsurface pollutants, including those from recent energy technologies and historic waste sites. Research into the flow of electrons can show how certain minerals and bacteria work together via reduction-oxidation reactions to shape the geochemical landscape at Earth’s near surface and possibly halt toxins from spreading. The scientific challenge is how to unravel complex communities of organisms and mineral assemblages in nature into key cooperative subsystems that can be studied in the laboratory to determine how they work. In a recent study, scientists at the University of Tuebingen, University of Manchester, and Pacific Northwest National Laboratory discovered that during the day, one species of bacteria withdraws electrons from the iron-based mineral magnetite. At night, another species adds electrons back to the mineral, where the electrons reside until the daytime bacteria are active. The phototrophic Fe(II)-oxidizing Rhodopseudomonas palustris TIE-1 and the anaerobic Fe(III)-reducing Geobacter sulfurreducens work together to use magnetite's iron ions as both electron sources and sinks under different day and night conditions. The researchers used a host of instruments to make this discovery, including transmission electron microscopy resources at the Department of Energy’s Environmental Molecular Sciences Laboratory. The research shows that the common iron oxide mineral magnetite can serve as a naturally occurring battery for two very different types of bacteria that depend on iron to survive, revealing that a single mineral can serve as a platform for microbial diversity in nature.

Reference: Byrne, J. M., N. Klueglein, C. Pearce, K. M. Rosso, E. Appel, and A. Kappler. 2015. “Redox Cycling of Fe(II) and Fe(III) in Magnetite by Fe-Metabolizing Bacteria,” Science 347(6229),1473–76. DOI: 10.1126/science.aaa4834. (Reference link)

Contact: Paul E. Bayer, SC-23.1, (301) 903-5324
Topic Areas:

  • Research Area: Subsurface Biogeochemical Research
  • Research Area: DOE Environmental Molecular Sciences Laboratory (EMSL)
  • Research Area: Microbes and Communities

Division: SC-23.1 Climate and Environmental Sciences Division, BER


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