In a recent scientific advancement, researchers from UCLA and UC San Diego’s Scripps Institution of Oceanography have developed an engineered gut bacterium capable of detoxifying methylmercury in mice. This breakthrough could potentially lower the risk of mercury absorption from fish-rich diets in humans.
The study, published in the journal Cell Host & Microbe, describes how DNA-encoding methylmercury detoxification enzymes were inserted into the genome of Bacteroides thetaiotaomicron, a common human gut bacterium. The engineered bacteria dramatically reduced methylmercury levels in mice fed a bluefin tuna diet, including pregnant mice and their fetuses.
Elaine Hsiao, UCLA associate professor, said, “We envision the possibility that people could take a probiotic to offset the risk of consuming too much methylmercury, especially when pregnant.” The motivation for this development stems from the persistent levels of mercury in seafood despite global reduction efforts. Amina Schartup, a Scripps associate professor, observed that “fish remains a major and culturally important part of the diet for many people around the world.”
Tests confirmed that the engineered bacteria were effective in reducing methylmercury in the intestines and further preventing its accumulation in the brain and liver tissues of the mice. Particularly in pregnant mice, the bacteria reduced methylmercury levels in both maternal and fetal tissues. As Kristie Yu, UCLA research scientist, noted, “By reducing dietary methylmercury in the intestine, the gut bacteria helped to eliminate it from the body before it could enter the maternal bloodstream and access the developing offspring.”
Even when tested with salmon, which contains lower methylmercury levels, the bacteria remained effective. Further tests with the bacteria as an oral probiotic in mice indicated the possibility of developing similar probiotics for human use.
Research support came from several prestigious organizations, highlighting the potential benefits of continuous federal funding for translating these findings to human applications. Hsiao and Schartup are actively working to enhance the bacterium’s efficacy in humans, emphasizing the critical need for ongoing research support.
