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How to Tell if Bacteria Is Colonized?

Bacteria is a unicellular microorganism that is generally not visible with the naked eye. However, when it becomes colonized the result is seen easily without the aid of a microscope. Colonized bacteria is a group of bacterial cells living in the same place. The colonies grow in clusters on a medium, numbering in the millions. They often appear yellow, pink or white.

Things You'll Need

petri dishes prepared with agar
bacteria from hands or mouth
cotton-tipped swab

Instructions

- 1
  Introduce bacteria onto the petri dish. Either touch the agar medium inside the dish with your fingers, or swab the inside of your mouth, cheeks and gums. Inoculate the medium with the bacteria by brushing the swab across its surface.
- 2
  Grow the bacteria. Cover the dish, tape it and store in a warm place upside down. Do not put in direct sunlight. Label the petri dish with a wax pencil with the date and source of bacteria: "mouth" or "hands."
- 3
  Observe for colonization. Growth should begin to occur within two to three days. If there is a foul odor and visible patches or clusters of bacteria on the surface of the medium, it is colonized.

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