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Every Man Is an Island (of Bacteria)

Shipud writes "There are ten times more bacterial cells in our body than our own cells. Most of them are located in our guts, and they affect our well-being in many ways. A group at Washington University has recently reported that although our gut microbes perform similar functions, it appears that different people have completely different compositions of gut bacteria: every man is an island, a unique microbial ecosystem composed of completely different species. One conclusion is that the whole division of bacteria into species may well be over-used in biomedicine."

14 of 193 comments (clear)

  1. Not news by PeterPlan · · Score: 1, Informative

    Common knowledge you can find in most microbiology or immunology textbooks.

    1. Re:Not news by Daniel+Dvorkin · · Score: 3, Informative

      "Common knowledge you can find in most microbiology or immunology textbooks" doesn't generally get a publication in Nature.

      I've worked with one of the authors (Rob Knight) of the most recent paper, so I have some idea of what their research entails. Basically they were expecting to find some diversity in bacterial populations between individuals, but the amount they found was the big surprise -- there is more genetic diversity between the gut bacteria population of any two randomly selected people than there is between two soil bacteria populations in a deep sea trench and on a mountaintop! How strongly the bacterial populations predict leanness vs. obesity was also far beyond any previously published result.

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      The correlation between ignorance of statistics and using "correlation is not causation" as an argument is close to 1.
  2. Re:the whole division of bacteria into species may by the_humeister · · Score: 1, Informative

    Agreed but only under the condition that I can't read the article because it's been slashdotted.

    Anyway, different pathogenic bacteria have certain antibacterial medicines that they're susceptible to and others that their not. Ergo, division of bacteria into separate species is not overused but necessary.

  3. Saccharomyces boulardii by Anonymous Coward · · Score: 1, Informative

    Admittedly this comment is only half-relevant, but I thought it would be informative for people to read about the many and varied praises heaped on Saccharomyces Boulardii, a tropical yeast which seems to have wonderful effects on gut flora.

    This probiotic appears to be (gradually) gaining recognition in the mainstream medical community.

  4. Re:can anyone explain this with actual science? by the_humeister · · Score: 5, Informative

    Each of your cells takes up 100-1000x more space than bacteria.

  5. Re:can anyone explain this with actual science? by Anonymous Coward · · Score: 4, Informative

    Prokayrotic (most bacteria) cells are much much smaller than Eukaryotic (your body) cells. Therefore event though you have less cells, those cells you do have weigh much more.

  6. Re:can anyone explain this with actual science? by Qzukk · · Score: 5, Informative

    Bacteria are a tiny fraction of the size of your cells.

    http://www.cellsalive.com/howbig.htm has a nifty little flash movie demonstrating the size difference.

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  7. Re:A real user... by Anonymous Coward · · Score: 4, Informative

    Bacteria do not digest your teeth. They eat the sugar that you consume. It's their #2 (as you called shit) that dissolves the enamel on your teeth.

  8. Re:Crohn's Disease by ColdWetDog · · Score: 4, Informative

    I've heard it speculated that this could be one of the causes of Crohn's Disease and Colitis. Can anyone here comment on this?

    Sure, it's possible: We know that Crohn's / Ulcerative Colitis have genetic predisposition - it's certainly possible that a susceptible person's immune system sees a particular bacterium or portion thereof or byproduct thereof and starts down the pathway of an autoimmune phenomenon.

    In light of the nature of the pathologic findings in Crohn's disease (see later) and ulcerative colitis, it has long been clear that IBD represents a state of sustained immune response. The question arises as to whether this is an appropriate response to an unrecognized pathogen or an inappropriate response to an innocuous stimulus. Over the decades, many infectious agents have been proposed as the cause of Crohn's disease including Chlamydia, Listeria monocytogenes, cell wall-deficient Pseudomonas species, reovirus, and many others. Paramyxovirus (measles virus) has been implicated etiologically in Crohn's disease as a cause of granulomatous vasculitis and microinfarcts of the intestine[30]; a proposed association between early measles vaccination and Crohn's disease has been largely disproved.[31] Another suggestion has been that the commensal flora, although normal in speciation, possess more subtle virulence factors, such as enteroadherence, that cause or contribute to IBD.[32]

    Among the most enduring hypotheses is that Mycobacterium paratuberculosis is the causative agent of Crohn's disease. This notion dates to Dalziel's observation in 1913 that idiopathic granulomatous enterocolitis in humans is similar to Johne's disease, a granulomatous bowel disease of ruminants caused by M. paratuberculosis.[33] M. paratuberculosis is extremely fastidious in its culture requirements, and some proponents of this hypothesis have speculated that the presence of M. paratuberculosis as a spheroplast may confound efforts to confirm the theory. Efforts to confirm this theory have included attempts to culture the organism; demonstrate it by immunohis-tochemistry, in situ hybridization, and polymerase chain reaction methodology; and empiric treatment with antimycobacterial antibiotics. Most investigation in this area has been inconclusive, providing insufficient evidence to either prove or reject the hypothesis.

    from Feldman: Sleisenger & Fordtran's Gastrointestinal and Liver Disease, 8th ed.

    So sure, maybe. Stay tuned.

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  9. Re:And it's ever changing by SlashBugs · · Score: 2, Informative

    Yes, and changing the population of gut bacteria in mice can control whether the mice stay thin or get fat.

    Briefly, mice with no gut bacteria were innoculated with bacteria from either obese or lean mice. The animals given bacteria from obese mice got fat, the animals given bacteria from lean mice stayed thin. There's a good writeup here.

    The details for humans aren't known, but it seems likely that it's basically the same for us. I used to know a guy who worked on classifying gut bacteria. He was always desperate for samples so almost all of his friends had, at some stage,kept a food diary then provided him with a turd in a box to work on. It's important work, but we were all secretly afraid that our samples were actually going into the construction of some sort of shrine...

    Also: farts are gas released by your gut bacteria, not directly from you. So if you have a particularly deadly brand it's not your fault, it's your bacteria.

  10. Re:can anyone explain this with actual science? by Anonymous Coward · · Score: 2, Informative

    Um, most of your body weight is water. And water is not cells :)

    Actually, the vast majority of the water in your body is found inside your cells, so in fact water IS cells (or rather cells ARE water)

  11. Re:What does it even mean? by smellsofbikes · · Score: 2, Informative

    Basically, species classifications are ambiguous and fuzzy even in higher animals, but they've served us really well as modelling tools, much like Newtonian physics, so we apply them everywhere. As long as we keep it in mind that they're not necessarily accurate, it's a fine idea.
    With that said, there are characteristics that are unique to some species of bacteria, and shared by all members of that species. It's not a terrible approximation. All Clostridium species are anaerobic, for instance. So if you have a huge population of bacteria, and you divvy them all up according to a whole raft of tests -- aerobic/anaerobic, gram+/gram-, pili/no pili, sporulating/nonsporulating and so forth -- at the end you have a whole bunch of groups, and within each group you find an extremely high similarity in DNA sequence, much more similar than a member from a different group. It's not a terrible idea to call that a species, even if it might not mean exactly the same thing that we mean when we apply the term to animals.

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  12. Re:the whole division of bacteria into species may by killtherat · · Score: 4, Informative

    Something doesn't make sense:

    There are ten times more bacterial cells in our body than our own cells. Most of them are located in our guts

    That means that over 50% of 90% of our body mass in in our guts? Well, the researchers are Americans...

    It's because microbial cells are much smaller then eukaryote cells. Imagine a bunch of basket balls surrounded by BBs.

    By mass its probably about two pounds.

  13. Re:Bacteria and weight by spazdor · · Score: 2, Informative

    Human tissue cells routinely outweigh bacterial cells by more than 100 to 1.

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