Re: Is it possible 2 carry out my experiment?what r e likely difficulties faced

Although this looks suspiciously like a homework question, I will comment here.

It sounds like you have all the equipment you need in order to do your experiment. That's good! There are a few issues with the experimental design, though.

The main problem is that you will get a mixture of bacteria (and probably fungi) with your toothpick. This is a problem because when you streak them on the plate, they will all grow. Among the mixture, there could be some that are resistant to the penicillin you have used, so it is possible that you will not see a clear zone around the drug. Even if some, or most, bacteria are sensitive to the drug, if there are enough resistant ones those ones will grow and thus prevent you from seeing sensitivity.

To circumvent the possible problem above, give some thought to making pure cultures. Isolate many bacteria from the finger nails, then choose several to make pure cultures, and test their sensitivity to the drug.

In terms of the technique, I would suggest making paper discs of penicillin and placing those on the agar, if possible. It's easier to see where you have put the drug. Also, you can make many of these at once and store them in your freezer.

You should also give some consideration to the type of agar you use. Different compositions will allow different types of bacteria to grow. So you need to do some research to determine the best kind so that you see growth of many organisms.

I think this should be enough additional info for you to get going. Good luck!

[Moderator's Note: In addition to Mark's excellent advice, we have several resources available on our site that can help you with your project. First, take a look at our bacterial culture FAQs:
http://www.madsci.org/FAQs/micro/culture.html
and also,
http://www.madsci.org/FAQs/micro/source.html

Then, take a look at this answer from our archives:
http://www.madsci.org/posts/archives/2005-11/1133190030.Mi.r.html

You can also search our archives for the words culture bacteria:
http://www.madsci.org/MS_search.html

We also have a few other bacteria-related FAQs that might be of intrest to you:
http://www.madsci.org/FAQs/micro/species.html

Good luck! -- SM]