Sully
Posts: 4
Joined: Thu Sep 06, 2007 5:02 am

Microbiology Project

Postby Sully » Thu Sep 06, 2007 5:14 am

I need some help on how to get started on a project involving microbiology.

My idea is to test the antibacterial effects of different brands of regular hand soap compared to brands of actual antibacterial soap.

I need help with:

- What type of bacteria to use (my teacher suggested I use staf. or just swab my hands).

If actual bacteria is suggested, I would like to know the personal risks involved with handling that bacteria.

- How exactly to go about setting up the experiment

I was thinking of simply creating a soapy solution with a controlled amount of water and controlled amount of soap.

Any ideas and suggestions would be helpful.


Thanks!

Lise Byrd
Former Expert
Posts: 95
Joined: Sun Sep 18, 2005 10:00 pm

Postby Lise Byrd » Sat Sep 08, 2007 2:19 pm

Sully,

Since your teacher suggested different ways for you to get bacteria, I'm assuming that working with bacteria is allowed for your school/ local science fair. Some fairs have rules and extra paperwork for projects that use bacteria.

If you are able to get a culture of a standard bacterium (for example, E. coli), it will reduce the number of variables in your experiment. You can ask your teacher or mentor about ordering a specific strain of bacteria; information about how harmful the bacteria strain is and what it will do to you should be available with the strain.

You can get bacteria from your hands or by swabbing often-used surfaces (like doorknobs or countertops), but you will culture many different kinds of bacteria, and they may not respond to your treatments in the same way. This may not be an issue, though, if you want to ask the broader question of whether antibacterial soap will kill more bacterial strains than non-antibacterial soap.

The Science Buddies website contains several project ideas similar to yours. These pages may give you ideas for how to proceed with your project:
http://www.sciencebuddies.org/mentoring ... ?from=Home
http://www.sciencebuddies.org/mentoring ... ?from=Home

Post again once you have a rough idea of your procedure, and we can look it over for you. You are also welcome to post if you have other questions.

Hope this helps!
Sonia

Sully
Posts: 4
Joined: Thu Sep 06, 2007 5:02 am

Postby Sully » Sat Sep 08, 2007 7:28 pm

Thank you so much Sonia!

Sully
Posts: 4
Joined: Thu Sep 06, 2007 5:02 am

Postby Sully » Sat Sep 29, 2007 9:46 am

I need help now in how to go about conducting this experiment.

I need to write a proposal for Monday. Here's the product:


"My proposal for the year-long science lab is to test the antimicrobial effects

of different brands of antibacterial soap compared to different brands of

normal soap. I will be using liquid as well as bar soap for this experiment.

The general set up for the experiment will include a controlled amount of

liquid and bar soap, either in mass or volume, and mixing the amounts

with a controlled amount of pure water. The bacteria that will be used will

most likely be a standard form of E.coli in order to reduce the number of

variables in the experiment. The procedure will involve preparing agar

plates with E. coli in an incubator and then adding a controlled amount of

the soap-water solution. The plate will then be left to sit for a set number

of days to see if the bacteria are completely destroyed or if it is still

present. The results will be measured in whether the bacteria are present

or not and in what quantity is it present in. A microscope may be used to

fully see if bacteria are present or not after applying the soap solution."



Suggestions are definitely welcome.

Thanks!

Lise Byrd
Former Expert
Posts: 95
Joined: Sun Sep 18, 2005 10:00 pm

Postby Lise Byrd » Sat Sep 29, 2007 11:44 am

Sully,

You have a good first draft. Some comments:

1. At the beginning of your proposal, you need to state why you are doing this experiment. What is the broader question you want to ask, and what do you hope to accomplish? For example, using antibacterial soap often makes the bacteria resistant to the soap. Are you asking a product-based question to find out which soaps still kill bacteria, or is it a biologically-based question that asks how many different kinds of antibacterial soap the bacteria are resistant to?

2. Ideally, you will want to decide the exact brands of soap to use. You might consider adding a non-antibacterial soap as a control.

3. Speaking of controls, you haven't mentioned any in your experiment. Controls will tell you whether your experiment is going as planned or if something unexpected has come up. For bacteria, standard controls are usually a plate that has bacteria but no treatment (positive control), and a plate that has neither bacteria nor treatment (negative control). The positive control tells you that the bacteria are indeed being killed (or not killed) by your treatment; the negative control tells you that your technique is sterile and you have not introduced other bacteria into your plates.

4. Ask your teacher what strain of E. coli s/he is able to get for you, and you can put the exact strain into your report. I don't think it's necessary for you to say that you chose this strain to reduce variables.

5. In terms of a time frame, bacteria grow very quickly, so you should be able to tell clearly after 1-2 days whether or not the treatment worked. You may use a microscope if you would like, but it should not be necessary.

6. Bear in mind that you may need to make dilutions of your bacteria so you get clear colonies on the plates, rather than a lawn. (I presume you will be counting colonies to decide how effective your treatments were.) Dilutions will be particularly important for your positive control, since you will be using it to decide what percentage of the original bacteria were killed by the soap.

7. As a general sweeper, the more specific you can make your procedure, the better. Find out what kind of agar your bacteria grow best on, the time and temperature for incubation, and decide on a starting amount of soap-water solution. (This may change as you perform your experiments.)

8. Final comment: What is your hypothesis? What do you expect to be the outcome of your experiment? Keep in mind that your hypothesis does not have to be proven true for your data to be valid.

Post if anything is unclear, or if you have more questions,
Sonia

Sully
Posts: 4
Joined: Thu Sep 06, 2007 5:02 am

Postby Sully » Sat Sep 29, 2007 11:49 am

Thank you for the information again.

This is just a proposal however, so a hypothesis and procedure are not truly being outlined here. But, all the other suggestions are terrific.

Thank you!

Lise Byrd
Former Expert
Posts: 95
Joined: Sun Sep 18, 2005 10:00 pm

Postby Lise Byrd » Sat Sep 29, 2007 11:56 am

Generally in a formal proposal, one wants to be as specific as possible with the procedure. However, if your teacher told you that you could describe generally what you will do, that should be fine.

I would definitely include a hypothesis, though. Your hypothesis is the most important part of your experiment, because it helps you (and those reading your report) focus your research and make sure it's not going off in a wild direction during the experiments.

Many students worry about getting their hypothesis "right", but again, in real science it doesn't matter whether or not you prove your hypothesis, just that you understand WHY your data prove/ disprove it.

Sonia


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