Bacteria Growth

Which Hand sanitizer kills the most bacteria ?

For my experiment I chose to see which hand sanitizer kills the most germs. I chose this because when the flu season comes around I want to make sure that the hand sanitizer I use is the best. I tested multiple surfaces to see which ones were the dirtiest. My hypothesis is that “Thieves” will perform the best. I think this because it has alcohol along with clove and cinnamon oils that would kill the most germs.I think this because many studies show antibacterial properties of cinnamon, clove, and other spices.

First I went around the school sampling the places that I thought were the dirtiest by swabbing them. I then took these swabs and plated them on agar plates. After that I put them in a incubator. After 2-3 days I identified the dirtiest plates-those that had the most bacteria growth. These surfaces were the science lab floor, science lab table and under a trash can. I tested three different hand sanitizers on the dirtiest plates. I had to count which plate had the most bacteria colonies with the hand sanitizer and without. I counted the bacteria and mold by getting graph paper and counting how many squares of growth on the plate. Finally, I multiplied every square of mold and bacteria by 36 soI could show how much millimeters of bacteria and mold there was on each agar plate.

After I collected my data it turned out that the spearmint did better by 36 millimeters. The spearmint had 216 square mm of growth, the thieves had 252 square millimeters of bacteria and mold, and the school hand sanitizer had 648 square mm of growth. My hypothesis was not correct because according to the data, the thieves grew more bacteria than the spearmint.

In conclusion, the hand sanitizer that killed the most germs was the spearmint.It is made by bath and body works and also has eucalyptus in it. It also has a higher percentage of alcohol than the “Thieves”. I learned that theoretically the more alcohol in a hand sanitizer will kill the most germs. Some possible errors could be that there wasn't an even amount of hand sanitizer placed on the various surfaces that I tested. The school hand sanitizer performed the worst it had 648 square millimeters of mold and bacteria. One way I could improve this experiment is by using more precise instrument to equally measure the amount of hand sanitizer placed on various surfaces.