The microbes within

July 14, 2010 • 6:25 am

If you missed “How microbes defend and define us,” Carl Zimmer’s piece in yesterday’s New York Times, go read it.  It describes new DNA-based work showing that we’re not only colonized by thousands of bacterial species—and the identities of those species differ from person to person—but that many of those bacteria are absolutely essential for our normal functioning.   Excerpts:

  • “Lungs have traditionally been considered to be sterile because microbiologists have never been able to rear microbes from them. A team of scientists at Imperial College London recently went hunting for DNA instead. Analyzing lung samples from healthy volunteers, they discovered 128 species of bacteria. Every square centimeter of our lungs is home to 2,000 microbes.”
  • “In addition to helping us digest, the microbiome helps us in many other ways. The microbes in our nose, for example, make antibiotics that can kill the dangerous pathogens we sniff. Our bodies wait for signals from microbes in order to fully develop. When scientists rear mice without any germ in their bodies, the mice end up with stunted intestines.”
  • “Some microbes can only survive in one part of the body, while others are more cosmopolitan. And the species found in one person’s body may be missing from another’s. Out of the 500 to 1,000 species of microbes identified in people’s mouths, for example, only about 100 to 200 live in any one person’s mouth at any given moment. Only 13 percent of the species on two people’s hands are the same. Only 17 percent of the species living on one person’s left hand also live on the right one.”

The most bizarre part: doctors use “bacteriotherapy” to treat some stubborn bacterial infections: patients can sometimes be cured by infusing their guts with a dilute solution of fecal matter taken from healthy people.

  • “Dr. Khoruts and his colleagues have carried out 15 more fecal transplants, 13 of which cured their patients. They’re now analyzing the microbiome of their patients to figure out precisely which species are wiping out the Clostridium difficile infections.”

As Zimmer shows, your body is not just an organism, but an ecosystem.

19 thoughts on “The microbes within

  1. We are Legion.

    This sort of discovery is what makes science so exciting. We think we understand something, only to find it to be more amazing than we ever guessed.

    1. especially the part that you can get infused-“perfused”?- with healhy faeces, albeit at low dilution

      1. One of the few ‘medicines’ where we’d prefer to think it was diluted to homepathic levels.

        Of course, the homeopaths have beaten the real doctors to this since all of their remedies contain as much homeopathically activated fecal matter as they do any of their purported ingredients.

  2. I can’t help but feel that this type of biological dependency will (eventually) prevent humans from ever colonizing other planets. It’s much more complicated than building spaceships and we can’t just take some seeds and a few cows and expect to thrive. I guess this opinion sounds silly, but no worse than fecal transplants.

    1. Not necessarily…after all, each and every human in a spaceship will be carrying their own colony of bacteria. So, you’re not just transmitting the person, but their intestinal flora.

      No, I think people are one of the great all-time methods bacteria have developed to transport themselves across great distances.

          1. not even sir francis or dr. newton should get away with bs; however on his behalf,fc, we simply dont know whether space panspermia happened….or happens

      1. Not necessarily a barrier, no, but likely some problems.

        – For reasons what may become the greatest ISS experimental/developmental spin-off, space conditions lower immune system efficiency. That ought to put our “ecosystem” in another state population-wise.

        – Radiation; same end result.

        But space colonists and their co-travelers will surely adapt, as they move away from our original biosphere and its own evolutionary trajectory.

        If we colonize the Oort cloud with its plentiful material and energy (fusion) resources, the extensive travel times will eventually effectively define some loose type of “biospheres”, long before we enter our neighbor stars own Oort clouds. I’m sure in such case future biologists will be plenty occupied with unraveling the dynamics.

  3. I imagine excited conversations between the people at Activia and the people at Fleets right now.

    1. Probiotics now come in many exciting new flavours, including ‘bob,’ ‘charlene,’ and ‘coyneberry.’

    1. Angier also happens to be an atheist. Her “My God Problem” is very much worth reading.

      Wherein she writes: “…what keeps most scientists quiet about religion? It’s probably something close to that trusty old limbic reflex called “an instinct for self-preservation.” For centuries, science has survived quite nicely by cultivating an image of reserve and objectivity, of being above religion, politics, business, table manners. Scientists want to be left alone to do their work, dazzle their peers, and hire grad students to wash the glassware. When it comes to extramural combat, scientists choose their crusades cautiously. Going after Uri Geller or the Ra‘lians is risk-free entertainment, easier than making fun of the sociology department. Battling the creationist camp has been a much harder and nastier fight, but those scientists who have taken it on feel they have a direct stake in the debate and are entitled to wage it, since the creationists, and more recently the promoters of “intelligent design” theory, claim to be as scientific in their methodology as are the scientists.

      But when a teenager named Darrell Lambert was chucked out of the Boy Scouts for being an atheist, scientists suddenly remembered all those gels they had to run and dark matter they had to chase, and they kept quiet. Lambert had explained the reason why, despite a childhood spent in Bible classes and church youth groups, he had become an atheist. He took biology in ninth grade, and, rather than devoting himself to studying the bra outline of the girl sitting in front of him, he actually learned some biology. And what he learned in biology persuaded him that the Bible was full of . . . short stories. Some good, some inspiring, some even racy, but fiction nonetheless. For his incisive, reasoned, scientific look at life, and for refusing to cook the data and simply lie to the Boy Scouts about his thoughts on God—as some advised him to do—Darrell Lambert should have earned a standing ovation from the entire scientific community. Instead, he had to settle for an interview with Connie Chung, right after a report on the Gambino family.”

  4. “I am large, I contain multitudes.”

    Walt Whitman wasn’t just being poetic there, eh.

  5. We are little more than mobile bags acting as taxi-cabs for bacteria.

    Human exceptionalism is over-rated.

  6. One reading of Parasite Rex told me all I need to know about Carl Zimmer.

    Namely, that he’s a prodigiously talented and fascinating writer, and is currently in my Top Five Authors list.

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