While it has been known for decades that bacteria known as Geobacter could clean up uranium waste, researchers at Michigan State University recently uncovered the biological mechanism behind the bacteria’s ability to do it.
Their findings, published online earlier this month in the journal Applied and Environmental Microbiology, could offer new methods of uranium bioremediation. Research is also being conducted on Geobacter’s ability to pull other toxic metals from waste streams.
Gemma Reguera, a professor of microbiology and molecular genetics at MSU, explains the process of how Geobacter captures uranium in a short YouTube video.
Shock and draw: In 2011, an MSU team led by Reguera discovered that charged protein filaments extruding from one side of the Geobacter cells are used to zap uranium, triggering chemical reactions that power the cells and trap the uranium in a mineral form.
But that’s not the whole story, as the filaments account for 75 percent of the observed trapped uranium. What was happening to the other 25 percent? The MSU researchers found the answer in lipopolysaccharide molecules, which coat the outer cell membrane and are capable of soaking up uranium like a sponge.
As the Geobacter soak up the uranium, they pack it into vesicles coated with the lipopolysaccharides. The bacterial cells release the vesicles and replenish their lipopolysaccharide coating to sop up more uranium.
“It’s a mechanism to remodel the cell surface and ensure maximum protection,” Reguera explained. “The cells produce some vesicles under normal growth conditions but increase production to get rid of the trapped uranium. We are now investigating how to scale up vesicle production. We could essentially make a factory for these vesicles to pull metals out of water.”