Life As You Can't See It: Bacteria on Everyday Objects

Overview

Objectives/Goals My project is to determine which has more bacteria living on it: a store bathroom door handle, a cell phone mouthpiece, or the bottom of a woman's purse. My hypothesis is the bathroom door handles will have the most bacteria on them. I chose this because I think more people have touched them than the bottom of the purses, and usually only one person talks on their cell phone. Methods/Materials First I prepared six petri dishes with nutrient agar. I then went to a local Walmart, moistened a sterile swab with sterile water, rolled it on the men's bathroom door handle, and swabbed it on the agar inside the petri dish. I repeated this procedure on a McDonald's bathroom door handle, two cell phone mouthpieces, and the bottom of two purses. Then I covered the dishes, and put them in a cool, dark place. I examined the bacterial growth on Day 2, Day 4, and Day 7. Results On the last day of observation (Day 7), I found that the bottom of my Grandma's satchel had the greatest variety of bacteria living on it, while my Mom's leather purse had the least of both variety and amount of growth. However, the bathroom door handles had the largest total area of bacterial growth on them compared to the purses and cell phones. Conclusions/Discussion My hypothesis was correct that the bathroom door handles had the most bacterial growth on them. This helps you by showing that everyday items are dirty with bacteria and you should clean those items every once in a while. (Or you should open bathroom door handles with paper towels when leaving.)

Competition history

• CSEF 2007 Microbiology · Entry J1401

Resources

• CSEF project summary ↗

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