Science Buddies: "Ask an Expert"

Doing a project to measure bacterial growth in Baby Food. Instructions call for Blood Agar for the Petri Dishes - haven't been able to find any. Can I use another type of Agar? There was mention on the site regarding using a beef broth but did not give a specific "recipe". Can I create something at home and if so How?
Thank you in advance for your advise! Parent of a 5th Grader

Hello
I included some links and the companies from which you can purchase blood agar

Fisher Scientific-www.fishersci.com/

Carolina-http://www.carolina.com/product/living+ ... pack+10.do

Amazon-http://www.amazon.com/Blood-Agar-EH-Pla ... B0017U0BV0

However I wanted to ask whether your child’s science fair allows blood agar because usually it is not considered viable for a student to use because of the potential of contamination from people. Students commonly use are Nutrient agar and LB(Luria Bertani)Agar.

I included the information regarding both agar’s from the science buddy website:

Nutrient Agar-Will grow the largest number of different types of microbes - fungi and bacteria. Yet, not all bacteria can grow on these. Some find it too rich, and others find it deficient. The nutrient in this is beef broth, and some extracts from yeast.

LB Agar-A subtype of nutrient agar, this is the general medium for microbiology studies and may be used for routine cultivation of not particularly fastidious microorganisms. Also, does not preferentially grow one kind of bacteria over another. The preparation for this agar is included in this link:https://www.sciencebuddies.org/science- ... Agar.shtml

Here is a link that provides the procedures needed to create your own agar medium in case you need it.http://www.umsl.edu/~microbes/pdf/homemademedia.pdf

Good Luck and if you need more clarifications or help please post.

Hi,

Sciencediplomat has given you very good advice on finding a source of bacterial medium that will be suitable for your project. I would like to add that bacteria that would grow in baby food would also grow well on nutrient agar or LB agar, so you don’t need blood agar. If you are studying a low pH food like fruit, you might also want to measure yeast and mold growth by using Sabouraud dextrose medium. This website gives the recipe for this medium.

http://en.wikipedia.org/wiki/Sabouraud_agar

The science buddies website has lots of background information on microbiological techniques that will be useful for this project.

https://www.sciencebuddies.org/science- ... ndex.shtml

This is a great project for a 5th grader. Do let us know if you have any other questions.

Donna Hardy

Hello,

I also just wanted to mention that whatever type of agar you end up using should be fine for your experiment because I don't believe that a difference in agar should make a significant difference in your experiment as long as you use that same agar for all your trials...

Good luck with the project!
Prasad