Monday, June 22, 2009

Monday, June 22, 2009

This gallery highlights a few particularly tough species of bacteria and archaea, a lesser-appreciated but equally-vast branch of the organismal tree.

Once upon a time, scientists routinely found life in places where it wasn’t supposed to exist. That doesn’t happen anymore, and not because the pace of discovery has slowed. If anything, it’s accelerated. It’s simply become clear that life can exist almost anywhere on Earth.After 3 billion years of evolution, life has flowed into every last nook and cranny, from the bottom of the sea to the upper edge of the stratosphere. From blazing heat and freezing cold to pure acidity and atomic bomb-caliber radiation, there’s seemingly no stress so great that some bug can’t handle it.This gallery highlights a few particularly tough species of bacteria and archaea, a lesser-appreciated but equally-vast branch of the organismal tree. Until the late 1970s, archaea was lumped in with bacteria, a confusion that speaks to the embryonic state of human microbial knowledge. Less than 1 percent of Earth’s microorganisms have been identified, and most of those won’t even grow in a lab.In some cases, the bugs are labeled as being uniquely durable, but the labels almost certainly won’t stick. Hardly a month passes without some newly characterized species setting a new microbial benchmark. Indeed, the very concept of species might not apply. Bacteria and archaea exchange genes “horizontally,” without the need for reproduction. It’s as if, while encountering someone on the street, you could trade for whatever genes came in handy at the time. This fungibility makes a mockery of old-fashioned, animal-based notions of species, and some microbiologists want to abandon the concept altogether.Speaking of the common gut bacteria Escherichia coli, biology pioneer Lynn Margulis once said, “If you put a particular plasmid into E. coli, all of a sudden you have Klebsiella and not E. coli. You’ve changed not only the species, but the genus. It’s like changing a person to a chimpanzee. Can you imagine doing that, putting a chimpanzee in the refrigerator, and getting him out the next morning, and now he’s a person?”It’s pretty hard to imagine, and the idea of microbes as an Earth-spanning ur-organism might take some getting used to. In the meantime, here are some examples of life’s awesome adaptability.Image: WikiMedia Commons/U.S. National Parks ServiceUpdate, 11:30am ET: The post originally mischaracterized archaea as being far less complicated than bacteria, and bacteria as possessing a cell nucleus — neither of which is true. They differ from each other profoundly, but not in ways that lend themselves to such hierarchical judgments.One thing bacteria and archaea have in common, however, is the lack of a nucleus or other membrane-bound cellular substructures. Only eukaryotic cells, which compose the bodies of plants, animals and fungi, have such structures.Pages: 1 2 3 4 5 6 7 8
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