The Richmond Mine in California hardly a relaxing vacation spot — its caverns can reach nearly 120 degrees Fahrenheit and 100 percent humidity, there's little oxygen, and its water is some of the most acidic anywhere on the planet, says Ed Yong at Not Exactly Rocket Science. And yet, researchers from the University of California, Berkeley, have been visting the mine for years to study the "wild" bacteria that thrive in such harsh conditions. "Bacteria grow within the cave, floating in thin films on top of its hot, acidic water," Yong says. "They are the lords of their extreme world, and they provide an unrivalled opportunity to study how wild microbes evolve."
In a recent study published in Science, Berkeley's Jillian Banfield and Vincent Denef describe the mine's bacterial ecosystem, which is ruled by a strain of Leptospirillum. There are only a few other species there, and those that come in from the outside usually die, Yong says. This makes the community small, well-defined, and self-contained, which makes it ideal for observing the evolution of the extreme bacteria without fear of outside contamination, he adds.
The researchers found that, "on average, the bacteria accrued 1.4 mutations in every billion DNA letters, each generation. That's near the top end of what people estimated based on lab experiments," Yong says. "Denef and Banfield’s study shows just how quickly wild bacteria can evolve. By fusing their genomes together, they can diverge greatly in just a matter of years, and rapidly adapt to environmental changes."