World's Fair


Aren’t these kind of pretty?

I have this nasty habit of owning several coffee mugs, and not cleaning them out after using them. So what inevitably happens is that I always have a mini microbial experiment in my office. Here are three examples, three different coffee cups (just so you have a bit of info on the media, I use a lot of sugar in my coffee, and also have a bit of cream).

It’s been a while since I’ve dug into a Bergey’s Manual so I figured it might be easier to see if there are any microbiologists out there who know what we have growing in these images (I especially like the top one – you can see these white areas of clearing).

What’s kind of curious, is that the top one also exhibited a different kind of growth compared to the bottom two (which conceivably may have the same organism). What’s that about? The colour of the mug?


  1. #1 Timon
    August 6, 2008

    I can’t identify them, but they look really freakin’ cool!

  2. #2 Helenmary
    August 6, 2008

    That is completely disgusting and amazing. How thick is the growth?

  3. #3 Stephen
    August 6, 2008
  4. #4 Dean
    August 6, 2008

    I have a neighbor who never (and I do mean never) cleans the coffee mug in his car. His comment is “It’s impossible for one-celled creatures to hurt you.”
    I do hope that this is not your philosophy? :0

  5. #5 nmc
    August 6, 2008

    It’s hard to tell from a photo but to me the middle one looks like most of it might just be congealed cream and sugar that sort of started to crystallize. I take my coffee similarly and have similar coffee cup habits; these photos are all too familiar…

  6. #6 Sandra Porter
    August 6, 2008

    I say sequence it and find out.

  7. #7 Interrobang
    August 6, 2008

    His comment is “It’s impossible for one-celled creatures to hurt you.”

    He apparently never met a necrotising streptococcus infection he didn’t like, I guess. (My mould allergy would also disagree with his statement.)

  8. #8 eddie
    August 6, 2008

    Bonsai blue cheese? I can see a craze starting.

    Are those white bits areas of no growth or growth of a white microbe?

  9. #9 David Ng
    August 6, 2008

    They’re a zone of no growth, or a clearing induced by whatever was there previously.

    The second cup does look like it’s just congealed matter, but the bottom cup looks as though there are colony type things?

  10. #10 Till
    August 7, 2008

    From experience I’d say the first one looks like mold, the others like thick sugar rests.

  11. #11 Avi Steiner
    August 7, 2008

    Just for a bit of ye olde pareidolia, the bottom of the third one looks (to the amateur eye) sorta like a disected eye. Eh?

  12. #12 IBY
    August 8, 2008

    God,they are pretty and cool, and disgusting and ugly at the same time.