Tuesday, May 06, 2008

Isolation Is Fun!

I'm not talking about sitting in a locked room for days upon days, I'm talking about isolating bacteria! Bacteria are everywhere, and depending on where you're considering, they're different from each other. On your skin alone, there are a multitude of different types of bacteria. These bacteria also differ from the bacteria in your mouth, which differ from the ones which are in your gut. Depending on the type of bacteria you're trying to study, you'll need to use different media (either liquid or solid) that you'll use to grow your organism on/in, grow it in the presence of oxygen (aerobic) or not (anaerobic), and supply it with different carbon and nitrogen sources, as well as additional nutrients (Ca, Fe, K, Mg, Mn, etc etc).

Different organisms respond to different culturing methods, and these methods can be exploited by the microbiologist to select for certain types of bacteria. In essence, you're "dissuading" a certain type of bacteria from growing, which allows the others to grow relatively uninhibited. That's what I'm doing today.

I have identified the major players in a bacterial community that we're really interested in, for use in agricultural applications (mainly to remediate animal waste). Now I'm trying to isolate them from each other so we can study them on their own. Now, we might not be able to grow each one of them, but I'd like to isolate at least the ones that are found the most abundantly in the system. Today, I start with a Halomonad. Given the name, these organisms typically like growing in conditions which have higher than normal salt conditions (halophilic - which means "salt loving" as opposed to halophobic which means "salt fearing"). Not all organisms can tolerate such conditions, so we'll use that to our advantage. So what we'll do is make up media containing a range of salt (NaCl) concentrations and plate out some of our bacterial containing solution. If all goes well, only the identified Halomonas strain will grow.

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