Identifying types of bacteria on Agar plate

[JanelleGanson]

My 7th grade son did the science project, "How Well Do Disinfectants Work?" using a piece of raw chicken and cleaners that claim to be "natural." Our agar plates have gotten some really great results! However, we'd like to identify what KIND of bacteria we see growing on the agar plates. There seems to be 3, maybe 4 different kinds of microbes growing... some are whitish-yellow smooth circular spots, some are white or gray fuzzy spots (like maybe mold?), and one dish grew something red. I'm pretty sure the one kind we are seeing (the white-yellow spots) is E. Coli, and some cleaners did great at killing the E. coli, but NOT great at killing the other, fuzzy looking microbe. As we compare results, it would be helpful to think through what kind of bacteria/microbes we are seeing. But I am having a hard time finding a website/resource that gives sample pictures/explanations (in simple terms) of how to tell exactly what we are seeing. Do you have a recommendation of where to look to be able to identify common microbes you might get from dealing with raw chicken?
Thank you so much for your help!
Janelle

[SciB]

Hi Janelle,
Welcome to Scibuddies. Growing and seeing microbes on agar plates makes a great project and introduction to microbiology, but I'm afraid identifying the bacteria and fungi is beyond the resources of home or high school. Appearance alone is no proof of species. There are many bacteria that make yellowish white colonies, including E. coli, so you cannot conclude that you have a certain microbe without subjecting the colony to a number of specific diagnostic tests.

Also, be VERY careful handling these plates and do not open the lid. There are some harmful human pathogens that can be growing on the agar and they can make you very sick. I always seal the lids to the base with tape so they cannot come off by accident. And after you have photographed the colonies, immerse the plates in 10% Clorox for several hours to kill the bugs.

If you want to learn more about how labs identify specific bacteria, there are many lectures and videos on Youtube:

https://www.youtube.com/watch?v=cMVyrrdgaYk

If you have any more questions, please let me know.

Scibee

[JanelleGanson]

Thank you so much for your help! I guess as we analyze results, we will refer to each colony by it's characteristics. (i.e. "Agar plate for Disinfectant 1 grew multiple colonies of yellowish-white bacteria but no fuzzy mold, whereas Disinfectant 2 grew two different colors of mold, but no yellowish-white bacterial colonies.") If you have any other suggestions on how to communicate the analysis our data, your thoughts would be welcome.
Thank you so much!

[SciB]

Hi Janelle,

Sorry I missed your question for so long. I did not get a notice in my email.

Your method of stating the results is perfectly fine. That is how the scientists of earlier centuries did many observational experiments before they had the sophisticated instruments and tests we use today.

The one thing to be sure to do, which you probably already thought of, is to take pictures of each agar plate and display them on your project board with labels and a caption telling what was put on the plate. If you can get some close-up lenses for your smartphone then you can take some close-ups of the growth. The colonies might not show much, but I think the fuzzy molds could be quite interesting. You might be able to see the spore-bearing organs. Here's a cool video that explains how to use a 10X macro lens with a smartphone: https://www.youtube.com/watch?v=vQqmyY177Oc

I think this lens might be a little pricey but it really look like fun!

There are a lot of other close-up lenses that you can buy quite cheaply. I have a 10X magnifying eye loupe that I taped over the phone's lens and it took great close-up pictures of bugs.

Hope this helps. Please post again and I will make sure that I see it this time!

Sybee