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ID: 281204 • Letter: S
Question
s from the Internet can contain viruses. Unless you need to edit, it's safer to stay in Protected View Enable Editing Oniginal culture 1 ml 1 ml 1 ml 1 ml 1 ml 10 ml 99 ml 9 ml 9 ml 9 ml 9 ml 1. Use the above dilution scheme to answer these questions: A. What is the total dilution factor of each tube (A, B, C, D, and E)? B. You plated 1.0 mL from tube D and, after incubation, you counted 158 colonies. You also plated 1.0 mL from tube E and, after incubation, you counted 20 colonies? How many bacteria TOTAL were in the original culture? (Hint A colony count of 30-300 colonies provides accurate results)Explanation / Answer
1) A) The dilution factor of tube A is 1: 100 (1 ml culture and 99 ml medium) = 100
The dilution factor of tube B is 1: 10 (1 ml culture and 9 ml medium) = 10
The dilution factor of tube C is 1: 10 (1 ml culture and 9 ml medium) = 10
The dilution factor of tube D is 1: 10 (1 ml culture and 9 ml medium) = 10
The dilution factor of tube E is 1: 10 (1 ml culture and 9 ml medium) = 10
B) If we consider the tube E, we get 20 colonies from 1 ml of culture.
Then the 1 ml of original culture contains 20 X 106 colonies (bacteria)
Therefore, 10 ml of original culture contains 20 X 107 colonies (bacteria).
That means 2 X 108 bacteria.
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