Science Buddies: "Ask an Expert"

We're working on an investigatory project that tests the effectiveness of solar water disinfection. Here's what we planned to do:

1. Get tap or toilet water in a bottle
2. Take a small sample of it and put it on agar or growth medium
3. Let the bottle undergo solar water disinfection
4. Take a new sample of the water that has undergone solar water disinfection and put it on agar or growth medium

The thing is, we don't know what agar to use. The different types of agar got us confused.

Hello!

Perhaps you've seen this already, but here is a link to our page about agar: https://www.sciencebuddies.org/science- ... robes-agar

You're right - there's a lot of types of agar out there and that can be confusing. I'd mostly consider the ones highlighted in red; Luria Broth (LB) is common in student labs, as is the general (and boringly named) Nutrient agar. They'll support a wide variety of microorganisms, which is good for your experiment since you don't know (and don't care) about what kinds of specific bacterial strains are in your samples.

Hope that helps!