Tuesday, August 17, 2010

How do you determine how many bacteria there are in a certain place?

i was thinking of comparing anti-bacterial soaps for my science fair and was wondering how i would be able to test the effectiveness of each soap on a bacterial level.

How do you determine how many bacteria there are in a certain place?
you would have to culture the area. you would need some petri dishes (just regular agar plates will do) - you can buy those on the internet (maybe a medical supply store),





for the project i suggest using your kitchen table as the subject area (use the table as normal for a few days without cleaning it). you want to divide the table into sections (mark it off with tape) - lets say you are testing 2 soaps so you'll need 3 sections b/c you'll want one section as a control (doesn't change - no soap). cultural the areas - the petri dishes should come with instructions or swabs but if not use clean q-tips (ones that just came out of an un-opened package - b/c you want them to be sterile). rub the q-tip on the section of table the rub it on the agar in the petri dish, do the same for all sections. wash the table with the desired soap (make sure your cleaning devices are all new, straight from the package). let it air dry for a few minutes then swab the table again rubbing it on a new petri dish. the petri dishes will need to be placed in a warm area (not direct light - bacteria likes to grow in the dark). be sure to take pictures, label your petri dishes. read instructions on petri dishes (if it comes with them) - make sure not to contaminate the dishes, don't leave the agar exposed to the air (only while you are rubbing the q-tip on).








website for agar plates (about $10 for 6) : http://www.sciencekit.com/category.asp_Q...
Reply:aww thanks. i hope you use this experiment. let me know how it works out. Report It

Reply:You have to take a culture of the area, and get it tested, or look under a microscope.
Reply:It's a bit difficult to do it for a science fair, as it requires some material. But take a look at http://www.disknet.com/indiana_biolab/b0...


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