(Blacksburg, Va., May 18, 2001) -- For decades, people have been interested in how microbes attach and release from mineral surfaces. The interaction is fundamental to the way microorganisms are transported through water treatment facilities, the effective use of agrochemicals, or the movement of toxic metals in ground water, for instance. But the forces between the molecules at the surfaces of microbes and minerals had never been measured.

Now, a Virginia Tech graduate student has invented a technique called biological force microscopy and he and his major professor have used it to determine what happens when Shewanella, a microorganism found in most soils, meets goethite, the most important iron oxide in soils worldwide. The research provides some of the first evidence of recognition between a living organism and an inanimate object such as a mineral.

The research will be featured in Science on May 18, 2001, in the article, "Bacterial Recognition of Mineral Surfaces: Nanoscale Interactions Between Shewanella and a-FeOOH," by Steven Lower, Michael F. Hochella Jr., and Terry J. Beveridge. Lower, soon to begin work as an assistant professor at the University of Maryland, College Park, invented the technique while a Ph.D. student in geology at Virginia Tech. Hochella is professor of geochemistry and mineralogy at Tech, and Beveridge is with the microbiology department at the University of Guelph.

Respiration is the process by which living things, including humans, break down carbohydrates to produce energy. Shewanella use oxygen to breakdown carbohydrates (breath); but, if there is no oxygen, the bacteria use iron3 (Fe III) to breath. This ability has a significant impact on the way minerals dissolve and the movement of iron in the environment.

So the researchers looked at Shewanella and goethite, the iron oxide known for turning soil yellowish. "The bacteria use the mineral as a terminal electron acceptor," Hochella sa
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Contact: Steven Lower
slower@vt.edu
540-231-8575
Virginia Tech
17-May-2001