Metallic mercury is fairly toxic already, but when it gets into the environment, bacteria that live in oxygen-free environments like sediment convert it to methylmercury, which increases its toxicity to animals, including people.
As researchers at Zhejiang University (Hangzhou, China) and the University of Maryland have recently found, there’s a natural way to protect plants — and even some fish — from methylmercury accumulation. A fungus called Metarhizium robertsii that has a symbiotic relationship with many crops not only can increase their yields and protect them from insect invasions, but it can also absorb and detoxify methylmercury, allowing the plants to grow with minimal mercury accumulation even in polluted soils. The fungus can even remove methylmercury from freshwater and saltwater.
Not only that, but they also identified the fungal genes responsible, and when they added another copy, the fungus became even more effective at protecting plants and cleaning up water. We’ll learn all about these new findings in the upcoming November 22 issue of the Proceedings of the National Academy of Sciences.
Since Metarhizium fungus grows on roots naturally, the authors were curious to see whether this relationship might help plants do better and/or accumulate less mercury from contaminated soil. So they grew plants in soil with levels of methylmercury or Hg2+ that are typical of harmfully contaminated sites.
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