Biocurious is a weblog about biology, quantified.

Name that contamination!

by PhilipJ on 26 August 2006

BioCurious indeed. I was cleaning out my old plates from the fridge this afternoon, and came across this fine specimen (pictures are from the top and through the agar, respectively).

The black dot in the middle of the second picture there is curious, as it seems to lie on one of my streak lines. Anyone have any ideas what it might be?

Whatever it is, it either ignores ampicillin, or the amp has long since stopped working. I should also mention that these plates have been sitting in the fridge since the June 2nd.

  1. Bill Hooker    4377 days ago    #

    The amp is dead—rule of thumb is one month cold and dark, a few days any other conditions—and the Thing is probably fungus of some sort. I don’t actually know how to be certain without either microscopy or waiting to see if it develops spores/fruiting bodies/filaments/whatever.

  2. Aaron Dale    4376 days ago    #

    The red pigmentation reminds me of prodigiosin, a red pigment made by the genus of bacteria Serratia. But I’d agree it looks more like a fungus, and your Ap has probably had it.
    As a general rule of thumb, make some glycerol sticks and streak out onto fresh ApLBA every time you want to use your bug.

  3. Lubos Motl    4372 days ago    #

    I would appreciate your comments about theoretical biology, re: Mohammed AlQ.:

  4. Travis    4372 days ago    #

    The amp should be fine. The color is the same that yeast have when they have a problems with adenine metabolism. Some bug mutated and can resist amp, but is very sick :)

  5. Sandra Porter    4367 days ago    #

    Why not stain a bit and look at it under a microscope?

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