Contamination

I came to lab today to find that all of my C. elegans plates are contaminated again.  Woo. To give you a sense of what that means I took some pictures.

C. elegans is a small roundworm. It’s adult size is about 1 millimeter so it is treated in most respects as a microorganism.  This lab raises the worms on Nematode Growth Medium plates which are an agar plate with certain salt concentrations that make it an ideal place for worms to live.  These NGM plates also happen to be great places for other things to live. Things like fungus and bacteria. Unfortunately when you want to do controlled studies on worms you can’t have these other things living with the worms because they could be secreting toxins or otherwise making the worms not the same as the worms on the next plate over. This means that when your plates get contaminated you need to toss them or isolate clean worms from them.

This is an NGM plate with OP50, a strain of E. coli that the nematodes feed on. This plate is good. No colonies of other stuff is growing. These bacteria are added to the plate before the nematodes.

This is a picture of some more NGM plates with OP50, but without nematodes. These plates, however have colonies of some other organism growing and will eventually become covered by this invading contaminant species.

This plate has nematodes on it that are contaminated with some fungus or other junk. The yellowish cloudy stuff is what you don't want.

In short, it’s hard to keep junk from growing on your plates where you want nematodes and only nematodes. I go to great lengths to keep them clean, wearing a mask and gloves, working in the clean hood (sterilized with UV light), spraying everything with ethanol before using it, and minimizing the amount of time the plates spend with their lids off.  I must be doing something wrong, though because this keeps happening.

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  1. infamousginger
    July 9, 2010 at 3:21 AM

    Ethanol takes a bunch of minutes to sterilize a surface and won’t get all types of micro-organisms. Try bleach. That is better.

  2. July 10, 2010 at 11:32 AM

    Sounds like a real pain. Good luck

  3. Ms Naj
    July 13, 2010 at 8:54 AM

    Kevin, the lab contamination sounds very frustrating-hang in there. You’ll figure it out. Otherwise, it sounds like you have make some nice friends and are having a good time.

    Ms Naj

  4. Vincent Lee
    January 20, 2011 at 12:21 AM

    just started working on C. Elegans. they’re hard to manage. Still working on the same research?

  5. January 21, 2011 at 12:03 AM

    No, I was just in China for 10 weeks this summer. I’m not currently doing any research but even while I was there I switched over to working on E. coli because I didn’t like the C. elegans project

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