Microbiology Answers

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10 grams of soil are placed in 40 ml of water (A). One ml of (A) is placed in 99 ml of water (B) 0.01 of (B) is placed in 9.99 ml of water (C). Dilutions (B) and (C) are plated in triplicates 0.1 ml in each plate.

After 24 hours incubation at 37 degrees Celsius, these are the results:

Plate B-1 counted 102 colonies  

Plate C-1 counted 10 colonies

B-2 counted 152 colonies

C-2 counted 12 colonies

B-3 counted 111 colonies

C-3 counted 11 colonies

Calculate the number of bacteria per gram of soil. (Show ALL calculations!)