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Fighting an Almost Invisible Pest

Ryan Harvey, a doctoral student who works as a research assistant in Judy Wall’s laboratory, demonstrates how a specialized machine known as the MerX can measure the amount of methylmercury in a given sample. “She’s very patient with me, which I appreciate,” he says of Wall. “Not a lot of other people would give you that sort of time.” Images courtesy of CAFNR News. 

A glass vessel containing a nutrient solution — made pink by an oxygen indicator called rezarurin — bubbles in Judy Wall’s laboratory. The solution is used to allow sulfate-reducing bacteria to grow on biofilms inside a reactor. The biofilms will later be tested for methylmercury.


They are all around us, raising trouble in their wake. They are so small, though, and silent that most of us have no idea they exist. But not Judy Wall. As a Curators Professor of Biochemistry who has been at the University of Missouri since 1978, Wall has spent her career driven by the fascination of microbes that corrode ferrous iron metal — among their list of crimes.

Wall started her career studying hydrogen production for a number of years before switching her focus to these microbes that can only live in the absence of air. “I then realized that these microbes also have a huge deleterious impact on human activities that we don’t even think about, we just pay for it,” Wall says. “We’re so used to it. We don’t pay any attention to it.”

One of those forms of payment came in the mid ’80s when every gas station in the U.S. had to switch from bare steel storage tanks to plastic or fiberglass tanks to prevent gas leakage from corrosion caused by the metabolic processes of sulfate-reducing bacteria, which has been the focus of her research for many years.

It turned out that this type of bacteria — that she affectionately calls her “bugs” — lives in water and plays an important role in the methylation of mercury in the environment, a process that produces a deadly neurotoxin.

After mercury is emitted into the atmosphere through burning coal and volcanic eruptions, it is oxidized and then comes back down to the earth’s surface as ions in rainwater. The mercury then becomes methylmercury in the sediment of waterways, such as rivers and lakes, where it is taken up by aquatic organisms such as phytoplankton, which are then eaten by fish. As the food chain progresses, methylmercury accumulates along the way.

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About this Story

Campus: Extension
Key words: Agriculture, Health, Innovation, MU Campus, Science, Teaching, Technology,
County: Boone

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