Well, I see that I’ve been remiss in not posting anything on bacteria in over a year. I was thinking about this recent Miller-McCune article on the matter as Kim has just recovered from a case of “walking” pneumonia. I went in with her for her 37 week OB appointment and when she complained about the nagging cold she just couldn’t shake, the doctor figured out she was actually suffering from pneumonia. A couple of doses of Zithromax later and she underwent an amazing transformation back to good (though, still miserable from pregnancy) health. The Zithromax did a number on what was likely a bunch of nasty Mycoplasma pneumoniae.
The Miller-McCune article is about some of the amazing things scientists are finding that bacteria are capable of (besides giving humans nasty infections in their lungs). Apparently, they are capable of much more sophisticated behavior than we previously realized:
A few scientists noticed in the late 1960s that the marine bacteriaVibrio fischeri appeared to coordinate among themselves the production of chemicals that produced bioluminescence, waiting until a certain number of them were in the neighborhood before firing up their light-making machinery. This behavior was eventually dubbed “quorum sensing.” It was one of the first in what has turned out to be a long list of ways in which bacteria talk to each other and to other organisms.
Some populations of V. fischeri put this skill to a remarkable use: They live in the light-sensing organs of the bobtail squid. This squid, a charming nocturnal denizen of shallow Hawaiian waters, relies on V. fischeri to calculate the light shining from above and emit exactly the same amount of light downward, masking the squid from being seen by predators swimming beneath them.
For their lighting services, V. fischeri get a protected environment rich in essential nutrients. Each dawn, the squid evict all their V. fischeri to prevent overpopulation. During the day, the bacteria recolonize the light-sensing organ and detect a fresh quorum, once again ready to camouflage the squid by night.
And, of course, there’s the cool factoid I’ve loved to share for years:
Strictly by the numbers, the vast majority — estimated by many scientists at 90 percent — of the cells in what you think of as your body are actually bacteria, not human cells. The number of bacterial species in the human gut is estimated to be about 40,000, according to Daniel Frank andNorman Pace, writing in the January 2008 Current Opinion in Gastroenterology. The total number of individual bacterial cells in the gut is projected to be on the order of 100 trillion
Finally, I’ll throw in my little immune system brag that I have never once artficially interfered with this 90% of the cells in my body as I have never taken an antibiotic. Most everybody I tell this to is quite surprised, so I am curious how unusual this is (at least for a person with access to developed world health care).