Bacteria Science Fair Project - How should I go about this project? Suggestions? (Oct/30/2005 )
I am entering the local Science Fair, and my topic is: How do different antibacterials and antibiotics affect bacteria, and why. I was thinking I might use E. coli, but I 'm not sure. I was also thinking I would go about this project by placing a colony of E. coli under a microscope, estimate the amount of E. coli(by counting?) and then use an antibacterial or antibiotic, such as triclosan(used in most soaps), then count the bacteria left, and show the percentage that died after using triclosan, and I would repeat this with other chemicals. Please give advice if you think this won't work, or if you have a better idea. Thanks! --- crossbow1313@hotmail.com
The problem with that approach is that you'll be unable to tell live cells from dead cells under a microscope...
You'll either have to plate them at dilution and do colony counting, or you could do what hospitals do -- start with a solid lawn of the bacteria, then plop down a little filter-paper circle impregnated with the substance of interest. If it's harmful to the bacteria, it'll cause a zone of clearing around the circle...
See pictures of this type of approach here...
You'll either have to plate them at dilution and do colony counting, or you could do what hospitals do -- start with a solid lawn of the bacteria, then plop down a little filter-paper circle impregnated with the substance of interest. If it's harmful to the bacteria, it'll cause a zone of clearing around the circle...
See pictures of this type of approach here...
Alright, I see what you are saying, but that would be hard to measure. What I mean is, what unit of measure would I use to compare the affect on the bacteria with the different antibacterials/antibiotics? For example, if you were seeing at what temperature a balloon popped, you would measure in degrees, and if you were testing to see if more diluted formulas of acids effected plants, the unit of measure would be the percent of strength (percent of pure acid, 100% being absoluted, 5% being very diluted). What unit of measure would I use for your suggestion? How could I compare the effects of different antibacterials/antibiotics? Thanks---- crossbow1313@hotmail.com
I suggest you to measure the diameter of the clear zone created by the bac, and also the presence/absence of the clear zone
Or you could add the test chemical to the media at various strengths, or place drops of the chemical at various dilutions to see at what strength they inhibit growth.
Besides, triclosan in soaps, you may wish to try bleach and ethanol (70%).
homebrew and YS are wise. I also agree that the kirby-bauer method will be easiest.
greatape213, this is how antibiotic resistance to a patient's infection is determined, and allows physicians to prescribe the appropriate antibiotic for a given infection. The setup is quite easy, then you measure the mm of the clearance zone. each bug has it's own recognized zone widths to determine if it is susceptible or resistant (you're using e coli? those values should be easy to find; if not let us know and we can send it to you)
iodine, 409 cleaner, rubbing alcohol, toilet cleaner is always a good one....
Alright, I'll measure the diameter of the clearance zone as you suggested, thats a good idea. I now have to grow the bacteria; I'm planning on buying prepared petri dishes at http://secure.sciencecompany.com/Prepared-...ishes-C659.aspx , and following the instuctions at http://www.coscosci.com/sci-exper/petridishes.htm , but if you can look and see if that'd work that'd be great. I'll probably do three trials on the bacteria using each antibacterial/antibiotic, so I'll probably need 15 prepared petri dishes, but I have someone else paying for them. Thanks for the advice, and if you have any more suggestions, please give them! Thanks - crossbow1313@hotmail.com
I was wondering where you could possibly get some E. Coli. bacterium that doesn’t involve anything nasty
You can do multiple points (different concentration, or dosages of the antibacterial agent) on one plate. Just be sure to give enough space between spots of your innoculation. You may want to vary the amount of bacterial as well.