Bacteria make major evolutionary shift in the lab

by Mikasi | June 10, 2008 at 05:02 pm

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This brings to mind lectures my mother gave me about not leavingdirty plates or pizza crusts laying about in my room lest they growsomething. We'll it's a fortuitous thing that at least one persondidn't do what they were told.

Amajor evolutionary innovation has unfurled right in front ofresearchers' eyes. It's the first time evolution has been caught inthe act of making such a rare and complex new trait.

And because the species in question is a bacterium, scientistshave been able to replay history to show how this evolutionarynovelty grew from the accumulation of unpredictable, chanceevents.

20-some years ago this scientist started culturing E. coli. As ofnow he has 44,000 generations of them. Upon examining them hediscovered they had undergone a "profound change."

But sometime around the 31,500th generation, something dramatichappened in just one of the populations – the bacteria suddenlyacquired the ability to metabolise citrate, a second nutrient intheir culture medium that E. coli normally cannot use.

Indeed, the inability to use citrate is one of the traits by whichbacteriologists distinguish E. coli from other species. Thecitrate-using mutants increased in population size anddiversity.

Tis worth your while to read the rest of the article to see howthe attempts to duplicate the mutation in the other 11 culturesplayed out.