Agar is a polymer that, when placed in boiling water and then cooled, has a gelatinous form. Agar's chief use is as a culture medium for several micro-organisms. One of the foremost of these micro-organisms is bacteria. According to Science Buddies.org, the agar used in science experiments should have "good clarity" and should not have "metabolically useful" minerals and compounds. Vinegar and other substances can be added to the agar to determine how well it inhibits bacterial growth.
Step 1
Place the bacteria you are experimenting on in four spots on the agar plate. You can use different types of bacteria or you can use different concentrations of the same bacteria, depending on how large your petri dish is or the type of experiment you are performing.
Step 2
Mix several concentrations of vinegar. Use four separate beakers and pour a quarter ounce of vinegar into each. Mix the first beaker with a quarter ounce of distilled water, mix the second with a half ounce of distilled water, mix the third with a three-quarter ounce of distilled water and mix the fourth with 1 oz. of distilled water.
Step 3
Take a pipette and drop three drops from the first beaker and place it in the bacteria colony of the agar plate. Then take three drops from each of the other vinegar concentrations and place them in the other bacteria colonies. Place petri dishes in a cool, dry location.
Step 4
Observe the bacteria growth in each of the colonies. Write down your observations on how the colonies have been impacted the most by the vinegar concentrations. Those observations can include growth and color change.
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