Category Archives: Exploring the Microcosmos

While I’m away….

I’m at the annual meetings of the American Society for Microbiology, stuffing my head full of the latest research on microbes and best practices for microbiology teaching.

It’s a small world

For my micro peeps out there, here’s a few fun facts from the meeting:

  • Giant viruses (called giruses) are so big you can see them with a light microscope and they have large genomes (for viruses) that may include genes for their own tRNAs and some metabolic enzymes. This breaks the traditional view that viruses borrow all protein synthesis and metabolic machinery from the host. These facts, as well as some evolutionary analysis, resparks the debate about whether we should consider viruses as “alive” and include them on the big tree of life.
  • The dirtiest places in hotel rooms (most likely to have coliform bacteria) are light switches and TV remotes. Hypothesis is maids don’t have time to clean the little things.
  • Pseudomonas aeruginosa uses it’s green pigment as both an electron donor and acceptor, which helps it survive in the damaged lungs of CF patients (when oxygen levels get low and oxygen isn’t available as an electron acceptor). As a CF’s patients lungs get more and more damaged, the bacterium makes more and more pigment.
  • The Japanese were using pasteurization to control the types of microbes present in sake fermentation 300 years before Pasteur was born. Oh, and making sake is more like making beer than wine, and there’s several different varieties ranging from the sort of earthy toned stuff that best with food to a champagne style that tasted to me like alcoholic Sprite. (Yes, there was a tasting session following the sake talk. We have to have a little microbiology-related fun.)

Sake production is very much like making beer. The initial mash is made by inoculating the rice with koji mold (Aspergillus oryzae). The mold digests the starches to sugars. Then, yeast are added to ferment the sugars to alcohol.

  • Engineers who jumped over to biology started a field called synthetic biology that involves building new elements into living cells. This is different than genetic engineering where biologists take something that evolved in one cell and move it into another. These guys really think out of the box and build their own genes and regulators. One of the cool things they’ve built is a sort of genetic circuit that involves two genes, whose gene products each act as the repressor of the other. Depending on which inducer you add to the system, you can flip the genetic switch on or off. One cool thing they’re trying to do with this is engineer normal gut bacteria like Lactobacillus to detect pathogens like Vibrio cholerae. The idea is that you’d put the engineered bacteria into people’s guts (presumably in areas where cholera is a high risk). If the cholera bacterium entered the gut, one of its gene products would act as an inducer to the switch built into Lactobacillus, causing Lactobacillus to start transcribing and translating an antimicrobial to kill the V. cholerae. This is awesomely cool crazy stuff!

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