Science Buddies: "Ask an Expert"

My son's science project is to identify which part of the school has the most bacteria. We have several samples growing in petri dishes and we now need to identify which growths are molds, fungi, bacteria and which colonies. I am posting two pictures, it would be great to have some guidance.

...sorry having trouble posting pics.

Hi there,

Have you checked out this guide on the Science Buddies website? https://www.sciencebuddies.org/science- ... ates.shtml

It gives a pretty good description of how to identify whether growth on a plate is a mold, fungus, or bacterium. Molds are generally whitish/grey and fuzzy; some fungi can be as well. However, some other fungi, like yeast, look very similar to bacterial colonies. One thing you can do is if you have access to a microscope, you can resuspend a colony into some broth, spot some onto a glass slide, and look under the microscope. Typically, bacteria and fungi should look pretty different under the scope. However, if you don't have access to a microscope, then following the guide that I sent you and trying the best you could to identify the different growths is already great!

Let us know if you have anymore questions.

Connie