Bacteria and Agar plates

[eclara]

My project is to test remedies for "bad breath". The experiment is to eat garlic and count the bacteria colonies in agar with 1% concentration. The control is no remedy. The remedies are mouthwash, brushing your teeth, gum, Tic Tacs, Colgate Wisps, a baking powder solution, and Listerine breath strips.

1. What are the chemistry and biology aspects of this experiment? Each individual member of the group has to do their own biology or chemistry research to explain the science and I would like certain topics/concepts that I can research.
2. What is the type of bacteria in our mouth that I should be researching?
3. Is inoculation required for this experiment? It doesn't seem like something students can do at home. Are there any alternatives?
4. Would the colonies be distinct and easily counted? And after what period(s) of time should I count the colonies?

Thank you in advance.

[deleted-71615]

1. What are the chemistry and biology aspects of this experiment? Each individual member of the group has to do their own biology or chemistry research to explain the science and I would like certain topics/concepts that I can research.
Your project is testing the effectiveness of different bactericide in human’s mouth. You should research to determine the mechanism of each bactericide use in killing bacteria.

2. What is the type of bacteria in our mouth that I should be researching?
Here is a link with information about different types of bacteria that are found in human's mouth. http://webs.wichita.edu/mschneegurt/bio ... ure22.html

3. Is inoculation required for this experiment? It doesn't seem like something students can do at home. Are there any alternatives?
You will need to do a before/after swab and plate the swab in agar plate, you should consult your teacher to see whether there is biological hood and incubator available in school for you to use.

4. Would the colonies be distinct and easily counted? And after what period(s) of time should I count the colonies?
Whether colonies are distinct and easy to count will depend on the number of bacteria/colonies that will grow on the agar plate.

Michael

[eclara]

Thank you, Michael, for your quick reply.

I am still a bit confused about inoculation and incubation. I read more into inoculation and it doesn't sound as complicated as I thought. It's just the flame that scared me.
But are both required for the growth of bacteria? I was hoping only inoculation is required because I can't find enough information about the bacteria in our mouth and from garlic to know what to set the temperature in the incubator at. Apparently, the conditions for bacteria in our body is 32 degrees Celsius and a 5% CO2 atmosphere. I guess I will go with these settings, but I don't know how long incubation usually is.

[MelissaB]

Hi,

Yes, you should go with approximately body temperature to set your incubator at--that is the temperature at which these organisms have evolved to best grow.

You will probably start to see colonies after 1 day, but they may be too small to count until day 2 or 3. I would check them at least every 12 hours so you can count them before the colonies grow so big that they start running into one another.

Good luck!

[eclara]

Thank you Melissa for your help.

I don't think I can check it every 12 hours. The incubator is at school and I was hoping to do the experiment at home. I read that room temperature is all right; it's just that the growth would take longer.
Would not doing immediate incubation change the results? I could do the experiment at home and bring it to school the next day. Or I could try doing the experiment at school and check every 24 hours.

[MelissaB]

Checking every 24 hours should be fine. I would recommend that you keep it at school just because some of the bacteria may die if they are exposed to room temperature--probably not many, but you don't want to affect your results too much.

Good luck!

[eclara]

Thank you very much for the quick reply :]
I think all my questions are answered (hopefully). Now it's just time for me to settle all the details with my group. Thanks again Melissa (and Michael) for your help!