Science Buddies: "Ask an Expert"

I have a few questions on my experiment..Here is the link for my project idea:https://www.sciencebuddies.org/science- ... p013.shtml. I am going to be aided by a microbiologist in a local lab. I will be conducting the steps up to the title that says "Measuring the zones of inhibition." My helper (microbiologist) does not want me to perform the steps under that title. But she still wants me to take the project further after performing the first part. The three disinfectants that I will be testing for their resistance against E. coli are: mouthwash, bleach, and garlic powder/cloves. I am in 9th grade so I would like to take the project further after observing their results of growth in agar plates at different concentrations. Do you have any ideas on how to add more on to this experiment? One more question--The method of inoculating the agar plates with the disinfectants that is stated for this project under it's procedure has not been used in 30 years (says the microbiologist). The procedure says that I should soak filter paper disks with the disinfectants and then place those disks in the agar plates...I am not going to use this method. Do you have any other ideas on how to do this? I would like other people's inputs... Thanks!

Hi,

It’s great that you have a microbiology lab to work in; you are going to learn a lot. Unfortunately, I am not familiar with methods other than the classic procedure described in the Science Buddies project guide. There are standard methods for testing disinfectants listed in the website below; however, I could not find a free copy of the procedures. Ask the microbiologist you are working with for a suggestion.

http://www.astm.org/Standards/E2614.htm

The procedures for evaluating disinfectants are evaluated by an organization, AOAC International. Here is their website, and you might be able to contact this organization for more information on an up-to-date technique.

http://www.astm.org/Standards/E2614.htm

What type of equipment do you have available to work with? Perhaps you could develop a new type of test method.

Donna Hardy