Bacteria Don't Have Species :: Astrobiology Magazine ::

Bacteria Don't Have Species :: Astrobiology Magazine :::

"Astrobiology Magazine: You have argued that bacteria don't have species. I wonder if you could explain that idea.

Lynn Margulis: Bacteria are much more of a continuum. They drop their genes all the time. Like we say in What is Life?, it's like going swimming in a swimming pool, going in blue-eyed and coming out brown-eyed, just because you've gulped the water. Obviously, animals don't do that. But that's what bacteria do, all the time. They just pick up genes, they throw away genes, and they are very flexible about that.

Say you have a bacterium like Azotobacter. This is a nitrogen-fixing bacterium. It takes nitrogen out of the air and puts it into useable food. Nitrogen fixing is a big deal. It takes a lot of genes. If you put a little something like arsenium bromide in a test tube with these organisms, and put it in a refrigerator overnight, lo and behold, the next day the cells can't do this anymore, they can't fix nitrogen. So by definition you have to change them from one genus to another."