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Microbial News at ASM

May 24, 2014

So what did we all learn at ASM, the American Society for Microbiology meeting 2014?

  • Bacteria you eat may prevent osteoporosis (bone thinning). Don’t all go out and buy probiotics, because health foods are unregulated and make outrageous claims. However, Lactobacillus reuteri makes a hormone-like molecule that does prevent bone thinning in mice. We saw slides of bones with and without. Furthermore, the bone-protective molecule inhibits development of cells that eat bone (osteoclasts). The doctors think that if post-menopausal women consume L. reuteri in some form, it may maintain bone density with fewer side effects than estrogen treatments.
  • Bacteria have a sense of touch. Before they make biofilms (multicellular communities), bacteria can “feel” the surface they touch using touch-sensitive proteins. How the touch transduction works, we still don’t understand.
  • Bacteria tell eukaryotic microbes to become multicellular bodies. Much evidence shows how bacteria and viruses activate key steps of embryonic development and immune system maturation. Now, a case has been shown in which marine bacteria tell unicelled eukaryotes called choanoflagellates to join together in rosettes.

The choanoflagellates then eat the bacteria–or do they? Do some of the bacteria take up residence?
Leading to the hypothesis that bacteria invented multicellular life to provide them a home.

  • More evidence for the bacterial home hypothesis: Human placenta contains specific bacteria. A few percent of the placental mass consist of normal bacteria, related to those of our mouths. These normal placental bacteria are actually needed for normal birth.
  • Even the deadly fungus Cryptococcus can provide a way to treat brain diseases. Cryptococcus makes an enzyme (a metal-containing protease) that can sneak its way across the blood-brain barrier. We may be able to use this enzyme to help us get therapeutic drugs into the brain.
  • Some bacteria may signal the gut via cannabinoid receptors. Getting ahead of my science fiction story, where the alien invaders take over Earth by spreading cannabinoids.

Alas, though, the “don’t floss” suggestion from previous post turned out to be a joke. Yes, keep flossing, despite the researchers who adore the dental bacteria they study.

4 Comments
  1. May 25, 2014 11:19 am

    Now, a case has been shown in which marine bacteria tell unicelled eukaryotes called choanoflagellates to join together in rosettes.

    That is really interesting. I would like to get a reference to follow up when the paper is published. Do you recall the mechanism at all?

  2. May 25, 2014 3:19 pm

    The research I saw presented is not yet published. But the observation of bacteria signalling choanoflagellates to form rosettes is mentioned elsewhere, in the link I provided.
    Nicole King’s publication list includes a number of relevant articles:

    http://mcb.berkeley.edu/index.php?option=com_mcbfaculty&name=kingn

  3. May 25, 2014 4:27 pm

    Thanks Joan. I read the eLife article. I’m not sure why the incomplete cytokinesis of choanoflagellates is that relevant to the evolution multi-cellularity, but I get the key finding is the bacterial inducement of this condition and that the compound was identified. Biology just gets more and more complicated and fascinating as we discover more phenomena.

    • May 25, 2014 7:33 pm

      Great article. The reason incomplete cytokinesis is important is that it’s a key step of embryonic development for various invertebrate animals, such as insects (fruit fly Drosophila). Since choanoflagellates can go either way (single cell or multicell) this suggests that bacteria can trigger the multicell program, and thus may play a role in evolving a fully multicellular organism.

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