Expert: Florence M Rollwagen - 1/11/2009

Question
Simple question: My daughter is trying to grow bacteria for her science project.  I've researched how to grow it from home and every website says that I must buy an agar solution in order to grow bacteria.  Is there another way to grow bacteria without buying agar?  If not, do they sell Agar solution in speciality stores or must I purchase it on the Internet?

Thank you,

Johanna Izaguirre

Answer
Hi Johanna:  Thanks for your question.  Yes, growing bacteria at home is a labor intensive project requiring purchased agar or agar plates.

If you want to use agar plates, I suggest that you buy them ready-made.  Making them at home requires a lot of skill and practice (not to mention lots of mistakes!).  Here is a source (I’m not affiliated with them): http://www.stevespanglerscience.com/product/1748?gclid=CJmworaXh5gCFQwNGgodvyvhD...

You can buy agar at the store, it’s used in Asian cooking and as a gelatin substitute in kosher cooking.  It is non-nutritive, so for microbiology projects some protein and carbohydrate sources are added.  These can include partially digested soybean extract (TSA) or blood.  Making this at home is possible, but you would have to have some training.  Then you would have to have some sterile plates w/lids to grow the bacteria.

However, there are other microbiology projects easily done at home.  Often they use yeast (that you buy at the store for bread making) to examine what kinds of sugars they use.  You can also test sugar substitutes for their ability to support yeast growth (hint: they don’t!)

I searched for “kitchen microbiology” and found some interesting links:

http://www.microbeworld.org/resources/experiment/experiment_biosphere_in_a_bottl...

https://mywebspace.wisc.edu/cevrentas/outreach/outreachNew/Materials/  Scroll down to “Yeast in a balloon”

http://www.sciencebuddies.org/science-fair-projects/project_ideas/MicroBio_p008....  Instead of buying lime, you can use pickling lime (from the grocery) or lime tablets (from the aquarium store).  To make a saturated solution, just add the lime to water and keep stirring until no more lime can be dissolved.  There should be a few crystals at the bottom.

These projects will vary depending on the age of your daughter and how much help you’re willing to give her.

Hope this helps.  Write back if you have more questions.

FM Rollwagen, PhD