Academic journal article The American Biology Teacher

Accommodating Microbes

Academic journal article The American Biology Teacher

Accommodating Microbes

Article excerpt

In April 2010, the state of Wisconsin declared Lactococcus lactis its official microbe. This makes perfect sense because the bacterium is crucial to cheese making, one of Wisconsin's signature enterprises. The announcement prompted Lauren Schenkman (2010) to ask researchers in other states what they might name as their "microbe mascots." The answers included Bradyrhizobium japonium, a symbiont in soybean roots that fixes nitrogen, thus saving Iowa farmers a lot on fertilizer, and Nesiotobacter exalbescens for Hawaii because it is only found in a single lagoon on one of the state's atolls, Laysan. Some researchers took another tack, suggesting bacteria that are more notorious than useful: Salmonella typhimurium for North Carolina, where hog farmers have to be constantly on the lookout for it; and Acidithiobacillus ferrooxidans, a new visitor to Louisiana that arrived in Chinese-made drywall for rebuilding New Orleans and spews out foul sulfurous compounds.

Because this month's ABT theme is microbes, I decided to begin my column with this new way to "honor" them. I had pulled out my "microbes" folder and sorted the articles. First, I separated out those dealing with bacteria because I have to admit they are my favorite microbes. I am enchanted by their versatility. Then I further sorted into two piles: those that dealt with disease-causing organisms, and those that covered odd topics, like the one I've just mentioned, or some of bacteria's more intriguing adaptations. Obviously, pathogenic organisms are important research subjects, but I felt like being more positive; and in fact, I discovered as I studied the articles on adaptations that many of these are related to how microbiologists may finally control some of those dangerous bugs.

But before I get to that, I have to cover a couple of "gee-whiz" topics, such as one about a biofilm found in a mine in Queensland, Australia (Reith et al., 2010). The biofilm--that is, a slimy-coated bacterial community--can dissolve gold, releasing gold ions that are toxic to the bacteria. However, in true bacterial fashion, the microbes have a way of dealing with the problem: converting the ions into metallic gold nanoparticles that form lacelike crystals. These are a much purer form of gold, one that miners seek out. It might be possible to engineer the bacteria to fluoresce when they are purifying gold, and then they could be used to detect the presence of the metal in ore.

The Skin

In another intriguing piece of research, bacteria are being used not in metal detection but in hunting criminals (Fierer et al., 2010). No matter what the surface, bacteria live there, and microbiologists are finding that the microbes live there in very complex communities. One of the most fertile surfaces is the human skin. With new genetic techniques, researchers have discovered that there are many more microbes living on the skin than previously thought, and that the particular types vary from person to person. The variation is great enough that microbiologists at the University of Colorado, Boulder, decided to find out if they could use the bacterial communities left on fingerprint traces to differentiate between individuals. They found that the amount of material remaining on a computer key was enough to test, even when the key hadn't been touched in two weeks. This means that if there is only a partial fingerprint or a smudged one, there might be enough bacterial evidence to match it to a suspect. I have to admit that I am not a fan of criminal-investigation shows (too many autopsies), but this is fascinating stuff. Once again, bacteria come through with a solution for a detection problem.

In case a criminal is thinking of washing away all those bacteria, that's hardly a possibility, and in fact, a shower can actually expose a person to more bacteria. This is one of those research findings you may not want to read about. The reason once again has to do with biofilms, this time on the showerhead. …

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