flickering pictures

The New Scientist reports that over 20 years and 44,000 generations in the lab, a particular population of Escherichia coli (or E. coli for short) bacteria have evolved the ability to metabolize citrate, a nutrient that the bacteria normally can’t use. This is a big deal — something akin to humans developing the ability to thrive on a diet of grass and tree bark.

From the article:

Indeed, the inability to use citrate is one of the traits by which bacteriologists distinguish E. coli from other species. The citrate-using mutants increased in population size and diversity.

“It’s the most profound change we have seen during the experiment. This was clearly something quite different for them, and it’s outside what was normally considered the bounds of E. coli as a species, which makes it especially interesting,” says Lenski.

[…] the experiment stands as proof that evolution does not always lead to the best possible outcome. Instead, a chance event can sometimes open evolutionary doors for one population that remain forever closed to other populations with different histories.

Lenski’s experiment is also yet another poke in the eye for anti-evolutionists, notes Jerry Coyne, an evolutionary biologist at the University of Chicago. “The thing I like most is it says you can get these complex traits evolving by a combination of unlikely events,” he says. “That’s just what creationists say can’t happen.”

(In the interest of accuracy, many creationists don’t dismiss evolution entirely. This guy isn’t one of them.)

Now 44,000 generations is a lot of generations — about 880,000 years in human terms — and the general consensus is that major evolutionary change takes time. But just two months ago, your intrepid blogger reported on a National Geographic article on Italian lizards that evolved “never-before-seen ‘cecal valve muscles’ and an ‘expanded gut’ to help digest the island’s tough vegetation, as well as longer, wider heads that allow for a harder bite, to rip stubborn leaves off of sturdy plants,” all in just 37 years on an isolated island.

And in case you’re wondering, E. coli is the main “food poisoning” bacteria everyone’s worried about in ground beef. According to the U.S. Centres for Disease Control, it makes 70,000 Americans sick each year, and the University of British Columbia says it kills 1,000,000 children worldwide annually.

Story via Slashdot.
Image via Bacteria Busters. (They bust bacteria.)

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