Need help with bacteria identification

[ClaytonChloe]

We are involved in a Year 5 Science project exploring the effects of washing hands on bacteria production. We have grown lots of bacteria but are having difficulty identifying it. We are hoping someone could tell us what the bacteria on these Petri dishes are likely to be. Thank you.thumb_IMG_6236_1024 copy 3.pdf
We seem to be having trouble adding the photos into the post - all help appreciated.

[deleted-284605]

Hi! Sounds like a fun project. I actually did something similar back when I was a student and had the same problem. You'll probably never be able to conclusively identify the exact bacteria on your plates, but you can describe them in a few ways. One is to identify the shape of the colonies- are they flat? Raised? Are the edges crisp or wavy? This site shows some examples of different properties of bacterial colonies and how to describe them.

Do you have access to a light microscope? Perhaps your science teacher can help you find one. It's fun and informative to look at individual bacterial cells under a microscope and see what they look like. One of the many ways to classify bacteria is by their "morphology" - a fancy way of saying "shape." The main shapes you'll likely see are coccus (circular) and bacillus (rod-shaped), but there are others too. This is a great way to narrow down the type of bacterium without doing any additional tests.

Definitely send us your photo(s) though! I recommend uploading images to the site imgur, which will make a unique URL that you can paste into your message.

[ClaytonChloe]

Thank you so much for the prompt and useful response. We will use the information from the morphology site to describe the bacteria. Hopefully one of these links will show a photo of our bacteria to assist further identification.
http://imgur.com/wBLOJXB
http://i.imgur.com/wBLOJXB.jpg?1

[deleted-284605]

Thank you so much for the prompt and useful response. We will use the information from the morphology site to describe the bacteria. Hopefully one of these links will show a photo of our bacteria to assist further identification.
http://imgur.com/wBLOJXB
http://i.imgur.com/wBLOJXB.jpg?1

Hi there! Wow, that's a gnarly plate!!! Looks like you have several different organisms growing, including some sort of filamentous bacterium and possibly a fungus/mold.

I looked around a bit online and found a source saying that the main resident bacteria on skin (bacteria that live there all the time and should not cause health problems) is Staphylococcus epidermidis. "Other resident bacteria include S. hominis and other coagulase-negative staphylococci, followed by coryneform bacteria (propionibacteria, corynebacteria, dermobacteria, and micrococci). Among fungi, the most common genus of the resident skin flora, when present, is Pityrosporum (Malassezia) spp."

If you google for images of some of these microbes on agar plates, you may find that they look similar to some of the organisms growing on your experimental plate. I think that's as good as you'll be able to get without a ton of lab supplies and fancy equipment. Describe as best you can, show the photo, and don't hesitate to throw out a few guesses!

Good luck!

[324B21]

Oh how fun. You are in my wheelhouse right now with this experiment.

A lot of what I am seeing in that photo is indeed sluffed off skin bacteria (most commonly the aforementioned Staphyacoccus). You can tell by the circular nature, the yellow color, and lack of protrusions. When doing any sort of a plate (outside of the ones where you do this sort of thing on purpose) those yellow circles are the bane of lab scientists dishes.

Some of the most beautiful photos I have ever seen are dishes like this. Here is a link if you would like to see more:

http://www.today.com/health/striking-ph ... and-t25096

You all did an amazing job there! Hope this helps.

Elizabeth

[ClaytonChloe]

Thank you very much for these replies. We have really enjoyed completing this project and really appreciate you both taking the time to share your expertise.