Help with a garlic and bacteria science fair project please

[crazykim]

We need help with a science fair project please. This is an 8th grade project and my son wanted to do garlic versus bacteria. We took 12 petrie dishes, divided and filled each with agar. On one-half was either a clove of garlic, garlic powder or minced garlic with the other side containing no garlic. He then swabbed the toilet, the door handle the TV remote and rubbed the swab in each part of each petrie dish. After 10 days the bacteria has grown wild (doubling) in the sides of the petrie dishes with the garlic. What does this mean? Did we do the experiment incorrectly?

 

Thanks so much for your help with this.

 

We need help with a science fair project please. This is an 8th grade project and my son wanted to do garlic versus bacteria. We took 12 petrie dishes, divided and filled each with agar. On one-half was either a clove of garlic, garlic powder or minced garlic with the other side containing no garlic. He then swabbed the toilet, the door handle the TV remote and rubbed the swab in each part of each petrie dish. After 10 days the bacteria has grown wild (doubling) in the sides of the petrie dishes with the garlic. What does this mean? Did we do the experiment incorrectly?

 

Thanks so much for your help with this.

 

In reading over this, maybe I wasn't so clear. The swab from the toilet bowl was rubbed in 3 dishes, the swab from the door handle another 3 and the swab from the remote in the remaining three. His science teacher said not to try more locations as that would add too many variables.

 

Thanks agian.

[iNow]

I'm not personally an expert, just an interested reader... But my first thought is that perhaps the garlic transmitted its own bacteria to the dish... perhaps from your fingers while placing it there. I'm unsure if this is the case, it's just a thought. Maybe a biological expert will offer some ideas after me. In the meantime, best of luck in the project... and remember, experiments like this are never failures as long as you come away having learned something new.

[crazykim]

Thanks for your comment and good luck wish! No, the toilet, the door handle and the remote were swabbed with sterilized swabs brand new in the pack. Our fingers never touched the minced or powder garlic. It's the craziest thing to see how wild the bacteria has grown in those portions of the dishes!

[iNow]

I wonder if moisture and the sugars in the garlic played some sort of role... Hmmm... Where are those experts when you need them.

[Sorcerer]

Yes the garlic provided nutrients for bacteria to grow on would be my conclusion.

 

Although u'd have to look at the organisms under the microscope and have some knowledge of microbiology to confirm wether it was bacteria or fungi.

 

IMO the experiment was flawed, there should be a control with 2 seperate dishes, one with pure agar the other with agar and garilic only.

Edited December 31, 2011 by Sorcerer

[MichaelPenn]

Sorry if I'm not reading your post correctly, but I'm still unclear on your procedure.

 

For this experiment to have been more correctly executed, it would have been appropriate to do this:

 

1. Create 1 dish with pure agar only.

2. Create an identical dish with agar and garlic type a (minced, for example).

3. Swab a location (ie. door handle) and rub that into the pure agar dish.

4. Swab the same handle again and rub that into the dish with garlic type a.

 

Next, to help test the idea that the garlic transferred its own bacteria, create a third dish with pure agar and place the garlic on that, without adding any collected bacteria.

 

Then you'll allow the specimens to incubate for a while and observe the results.

Edit: The key to a scientific experiment is to anticipate/identify possible variables and influences on your results. A well-designed experiment would effectively account for these somehow, allowing you to determine that what you are observing hasn't been altered inadvertently. For example, if you don't have a plate with garlic and no added specimens, someone could say, "Well the plate with bacteria + garlic developed to a greater degree than the plate with only agar and bacteria because the garlic stimulated growth / provided nutrition for the bacteria / etc." and you would not be able to argue this point, nor would you be able to determine if that was actually the case at all.

Edited January 2, 2012 by Michael Kovich