Bacteria Culturing Science Exercises for Kids

Bacteria Cultures

Most of the materials that you will need to culture bacteria can be found at a grocery store or in your own home. You will need a container, a food source and a lid. You will also need a bacteria starter, which can be harvested from the surfaces in your home or school.

Purpose

The purpose of this experiment was to determine which disinfectant would most effectively kill bacteria.

I became interested in this idea when I was washing the counter and I wondered if the disinfectant I was using was better than another was.

The information gained from this experiment would help parents, health care providers, and food preparers to know which disinfectant to use to the best results for killing bacteria.

Hypothesis

My hypothesis was that bleach would work the best in killing the bacteria.

I based my hypothesis on Marie Clark, Microbiologist at Memorial Hospital, who said, "Bleach will probably work the best because it is an oxidant."

Experiment Design

The constants in this study were:

• The amount of disinfectant used
• The type of agar plates used
• The way the number of live colonies were measured
• The temperature and time of incubation
• The incubator
• The number of organisms there were to start
• That the disinfectants were opened from a new bottle for the experiment
• The time the bacteria and disinfectant were in contact before plating

The responding variable was how many bacteria were killed by the disinfectant after one night of incubation.

To measure the responding variable the percentage of surviving colonies was determined.

Materials