Lab 10 - Bacterial Growth II

November 7 9 2012 agar plate analysis colonies per

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Unformatted text preview: 10- 7 Lab 10. November 7- 9, 2012 19 Agar Plate Analysis •  Six agar plates inoculated with E. coli •  10- 7 through 10- 2 diluTons from your starTng concentraTon •  Inoculated with 1.0 mL per plate •  Start with the lowest diluTon that has visible growth. •  Count the number of colonies. •  Move to the next highest diluTon. It should have approximately ten Tmes the number of colonies. •  Repeat unTl the colonies are too numerous to count. •  The ideal range for accuracy is 30- 300 colonies per plate. 20 Lab 10. November 7- 9, 2012 Agar Plate Analysis EXAMPLE •  Six agar plates inoculated with E. coli •  10- 7 through 10- 2 diluTons from your starTng concentraTon •  Inoculated with 1.0 mL per plate Plate Dilu?on Number of Colonies 10- 2 TOO NUMEROUS TO COUNT 10- 3 TOO NUMEROUS TO COUNT 10- 4 TOO NUMEROUS TO COUNT 10- 5 TOO NUMEROUS TO COUNT 10- 6 144 10- 7 15 Lab 10. November 7- 9, 2012 Agar Plate Analysis (Colonies per plate) ÷ (1.0 mL diluted broth per plate) = Colonies per mL of diluted broth (Colonies per mL of diluted broth) ÷ (diluTon factor) = Colony- forming units per mL of original inoculum 21 Lab 10. November 7- 9, 2012 22 Agar Plate Analysis EXAMPLE (144 colonies per plate) ÷ (1.0 mL diluted broth per plate) = 144 colonies per mL of diluted broth (144 colonies per mL of diluted broth) ÷ (10- 6 diluTon factor) = 144 x 106 colony- forming units per mL of original inoculum = 1.44 x 108 CFU/mL of original inoculum Lab 10. November...
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