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What is a Microbe? Escherichia coli A microbe is a microorganism, a tiny living thing that is too small to see with your eyes. Microbes can be tiny plants, bacteria, fungi and other living things. Many microbes form colonies, which you can see with your eyes. A colony of bacteria will have more than one million microbes. 1

Beneficial Microbes Some microbes are useful. Microbes make yogurt from milk. Yeast is a microbe needed to make bread, beer and wine. The yeast in bread makes CO 2 gas, which make the bread fluffy. Microbes in the soil make the ground fertile to grow healthy green plants. Microbe Name Bread Wine Beer Yeast Yogurt Lactobacillus blugaricus Acidophilus Soil Diazotrophs: Cyanobacteria Rhizobia Frankia 2

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6 Draw what you see on your plates D C Your hands Test Swab Location: _________________ Did washing your hands kill germs? YES NO Were there germs in your test swab? YES NO

Germs are microbes that can cause illness. How do germs move from one person to the next? Sneezing, coughing, Touching with dirty hands How can we prevent sharing our germs? Wash your Hands. 3

4 Cell division Many microbes produce offspring through simple cell division. They have one parent instead of 2! One parent cells splits into 2 cells, the 2 nd generation. Each of the 2 cells splits into 2 cells to make 4. For bacteria one generation is about 20 minutes under the best conditions. Fill in the boxes to show how many bacterial cells will be in each box. Eventually there are so many that we can see a colony of bacteria.

5 ACTIVITY Does washing your hands really kill the germs on your hands? 1.Pick an agar plate with a line drawn down the center. 2.On the side of the plate with “D” gently rub your fingers 3.Wash your hands with soap and water and dry them. 4.Gently rub your hands on the other side of the plate with the “C” 5.Allow your plate to incubate with the agar side up for several days at room temperature. 6.After several days, DRAW what you see on the plate. Where do you think there are germs in your classroom? 1.Your group will pick a place test for germs. 2.Gently swab the location with a sterile Qtip. 3.Gently rub the Qtip on a new agar plate. 4.Allow your plate to incubate with the agar side up for several days at room temperature. 5.After several days, DRAW what you see on the plate.