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7 December, 2003

Something Is Growing In My Refrigerator!

While most people would be appalled to find things growing in their refrigerator, we are pleased to see the microorganisms that are growing on our plates. After just over a week of being grown on yummy agar at a “snuggly” temperature of 15 degrees Celsius, bacteria and yeast colonies can now be seen growing on our plates. The bacteria started showing up a few days ago, but the yeast have only just started making their appearance.

1. Dr. Laurie Connell opening the refrigerator

2. This is an example of one of our LB agar plates. Are these bacteria or yeast? (Hint: what is grown on LB agar?) Each little dot is a separate colony.

3. Laurie counting bacterial colonies. We place a dot directly on the bottom of the plate on top of each colony we count. The total number of colonies is then written on top of the plate. What is a way that you could estimate the number of colonies if your plate was completely covered in little dots?

4. A bag full of counted bacterial plates. Did you notice how Dr. Redman was able to estimate the number of colonies on some of our plates? We are interested in learning the total number of bacteria in the soil verses identifying species. Therefore, these plates will soon be autoclaved. Why must we autoclave the plates before disposing them? Yeast grow much slower than bacteria, so our yeast plates will be returned to the refrigerator.

5. Dr. Regina Redman reads off the number of colonies counted on each plate as Dr. Connell records them. Besides the number of colonies, what other piece of information would be very important? (Hint: did we collect our samples from the same place?)

6. Me looking at some of our yeast colonies under the microscope.

7. A lot of our YPD plates had these pink colored yeast.

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