If you’re like me, you’re not a big fan of dirty water. Canoeing in late July in northeastern Ohio always brought an awful green film of algae to the top of the water, discouraging our annual impromptu mud slides or jumping out of trees into the river. A tinge of color or specks of dirt in my drinking water will make me crinkle my nose, and a fly in my soda will cause me to push it aside.
A fly in my beer, on the other hand, after plucking it from the frothy goodness will cause me to tell it to spit it out.
But we’re kind of unique in this in the animal kingdom. Most animals don’t care if there is a deer urinating upstream in their drinking water. Others – like tiny little bacteria – even thrive on the minerals and organisms found in their aqua. In fact, some make use of some of the worst contaminates that nature can throw at them.
Take, for example, Geobacter bacteria. These little guys are so hardy, that they even make use of uranium in their habitat. Every animal from single-celled organisms to your grandmother needs energy to live. Your grandmother oxidizes the food she puts in her stomach at The Cooker ever weekend. Geobacter takes electrons from uranium, effectively oxidizing problematic uranium(VI) to uranium(VI).
To all you people who fell asleep in chemistry as much as I did and don’t have the correct Wikipedia page open, uranium(VI) is highly soluable and travels through groundwater easily, making it a prime suspect for spreading contamination. Uranium(IV), on the other hand, due to its loss of electrons is insoluable. So as these bacteria take energy from uranium to carry out their daily lives, they create solid uraninite that isn’t really able to spread anywhere.
This fancy trick makes Geobacter a prime candidate for helping to clean up environments where uranium contamination is a problem. Just give the bacteria a bunch of food, let them grow and pull the uranium right out of solution.
The small caveat is that nobody knew how they did it. True, it’s best not to look a gift horse in the mouth, but if scientists could understand the process, perhaps they could engineer bacteria to do it even better, or produce an artificial way to mimic the process.
Well, thanks to Michigan State University microbiologist Gemma Reguera, they’ve got it figured out now. Previous studies showed that the oxidation took place along the exterior of the cell or even within the cell envelope itself. This would be kind of odd, as uranium is pretty toxic stuff.
Reguera figured it out, though. The process responsible works through the bacteria’s conductive pili—tiny hair-like structures that extend from the cell that conduct electricity. Using some fancy genetic engineering and bacteria know-how, the team produced four strains of Geobacter: one without pili due to adverse temperatures, one without pili due to genetic mutation, a normal strain and one with increases pili due to genetic mutation. Sure enough, those without the tiny protrusions sucked at oxidizing uranium. Sure, they got some of it, but not nearly as much as the regular or enhanced strain.
Reguera and everyone involved hopes that this new information will help clean up some of the worst man-made pollution sites in the world.