Yeast to measure bacteria growth

[Goliath]

I am trying to assist someone with a science project. They are wanting to test bacteria left behind after washing your hands with different types of hand cleaners. They were told they could use yeast to do this. Can anyone help with how to do this?

thanks so much

[SGelman]

Hi Goliath,

I have not heard of doing this kind of experiment with yeast, but you can look at this project to get some ideas:
http://www.sciencebuddies.org/mentoring ... ?from=Home

If you do some searching on Google or any other search engine you should be able to get some helpful hints. Good luck!


Susan

[vtrip]

Im not exactly sure what you mean about using yeast to measure bacterial growth, but I have a suggestion for measuring bacterial growth. After the test subjects wash their hands, you could use a cotton swab and sample their hand. Then streak an agar plate with the cotton swab and see what grows. Here are a few links to help you:

http://www.sciencebuddies.org/mentoring ... ?from=Home

http://www.sciencebuddies.org/mentoring ... Agar.shtml

http://www.sciencebuddies.org/mentoring ... ates.shtml

http://www.sciencebuddies.org/mentoring ... ques.shtml

the last link is very important. Read the procedures and safety guidelines thorougly before you start, and if you have any questions, please post again.

[Goliath]

Her science teacher told her she could use yeast in petri dishes instead of agar but I had never heard of that. Thanks for your information.

[adance]

Hmmm...I don't think I've heard of using yeast to grow bacteria INSTEAD of agar. Normally, to grow yeast in a petri dish, you use agar. Yeast extract is usually part of what you put in bacteria-growth medium, maybe that's what your teacher was thinking of? The agar gives you a nice firm surface.
I think it should be pretty easy to find something you can buy to grow bacteria on; I wouldn't worry so much about the exact stuff you use to grow; I'd focus on what you're growing.

Amber

[Daniell]

Hmmm...I don't think I've heard of using yeast to grow bacteria INSTEAD of agar. Normally, to grow yeast in a petri dish, you use agar. Yeast extract is usually part of what you put in bacteria-growth medium, maybe that's what your teacher was thinking of? The agar gives you a nice firm surface.
I think it should be pretty easy to find something you can buy to grow bacteria on; I wouldn't worry so much about the exact stuff you use to grow; I'd focus on what you're growing.

Amber

Hi, researchers! Registered in here to ask what was the result of the experiment. Post it in here if you can.

[lilyc]

As Amber said, yeast extract is typically a main component of the growth medium in agar plates used for culturing bacteria. If you're interested, here is a recipe for growth medium: http://mcb.berkeley.edu/labs/krantz/protocols/agar_plates.pdf

It sounds like you are interested in seeing what strains of bacteria will grow after having used different kinds of soaps/hand sanitizers. You may want to wash your hands, swab your hands and then plate the bacteria, and then see what grows. Keep in mind, you might have a hard time growing the bacteria without an incubator (usually set to 37 degrees C).

But before all of that, you might want to look up background information on common types of bacteria that live on human skin, how soaps and hand sanitizers work to kill bacteria, etc.

[mbadtke]

I agree with Lily's post, I think the confusion is due to the fact that you use an extract of yeast in many types of media for culturing bacteria. Basically yeast are ground up and the chemical building blocks are added to the media to help the bacteria grow. Good luck with your project!

Matt Badtke