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Bacteriology Science Fair Project

Dog vs. Human Mouth Bacteria

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Dog vs. Human Mouth Bacteria | Science Fair Projects | STEM Projects
Do dogs or humans carry more bacteria in their mouths? Many people believe a dog's mouth is cleaner than a human's. This project puts that claim to the test. You swab the mouths of three dogs and three people at least two hours after eating. Each swab is wiped onto a marked section of a petri dish filled with agar. The dishes sit at room temperature for several days. After the bacteria grow, you compare the amount in each dish. The results show whether the old saying about clean dog mouths holds up.

Hypothesis

The hypothesis is that dogs will have more bacteria in their mouths.

Method & Materials

You will swab the mouths of dogs and humans, lightly brush the swab over marked area of petri dish, and keep petri dishes in a warm area.
You will need agar, petri dishes, sterile swabs, and a thermometer.

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Results

The hypothesis was correct - dogs had more bacteria in their mouths than humans. This proves that the old wife's tale that says that a dog's mouth is cleaner than a human's mouth is incorrect.

Why do this project?

This science project is interesting because it tests an old wives' tale and provides evidence to prove it wrong.

Also Consider

Variations to consider include testing different breeds of dogs and humans, testing different ages of dogs and humans, and testing different times of day.

Full project details

Additional information and source material for this project are available below.
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