What you can't see... can it hurt you?
Elizabeth M.
The purpose of this experiment was to determine if common objects contain potentially harmful bacteria. Some of the processes that were used in making this experiment were bacterial cultures and gram stains of bacteria. There were four sites tested in this experiment: a telephone receiver, a doorknob, and the boys' and girls' bathroom. The cultures were the first process performed. Using sterilized cotton swabs, each site was cultured twice. The swab was then rubbed against the agar in each petri dish. The dishes were put into an incubator and bacteria grew. The colonies were counted in each petri dish. It was found that the girls' bathroom had the most bacterial colonies (42, 10), followed by the doorknob (5,7), the telephone (2,6), with the boys' bathroom having the least amont of colonies (2,2). Gram staining was then executed. Using bacteria grown from the petri dishes, the different bacterial colonies were placed on a glass slide. The slide was passed through a flame and the gram stain chemicals were applied. The bacterial samples from the boys' bathroom were gram positive only, samples from the girls' bathroom, telephone, and doorknob turned up as both gram positive and negative.
After completing the experiment, it was concluded
that the girls' bathroom had the most bacterial colonies, the doorknob was
second, the telephone was third, and the boys' bathroom had the smallest
amounts of bacteria.