1. You are using a Petroff-Hausser counting chamber to determine the number of cells in liquid cultures.
(A) After diluting the original sample 100-fold, you place the dilution into the chamber. If you count, on average, 10 cells for each 0.2 x 0.2 mm square, how many cells per mL were present in your original sample?
(B) If you have a culture that contains 2 x107bacterial cells per mL of liquid, how many cells should appear in each 0.2 x 0.2 mm square of the counting chamber, on average?
2.
You are performing a viable cell count by plating serial dilutions of a liquid culture, using 0.1 mL of each dilution per plate. Assuming that the cells are 100% viable, for a culture that contains 4 x107bacterial cells per mL of liquid, which of the 10-fold serial dilutions (for example, 10-1, 10-2, 10-3, etc.) would you need to plate to obtain between 10 and 500 colonies per plate? How many colonies should appear?
1. You are using a Petroff-Hausser counting chamber to determine the number of cells in liquid cultures.
(A) After diluting the original sample 100-fold, you place the dilution into the chamber. If you count, on average, 10 cells for each 0.2 x 0.2 mm square, how many cells per mL were present in your original sample?
(B) If you have a culture that contains 2 x107bacterial cells per mL of liquid, how many cells should appear in each 0.2 x 0.2 mm square of the counting chamber, on average?
2.
You are performing a viable cell count by plating serial dilutions of a liquid culture, using 0.1 mL of each dilution per plate. Assuming that the cells are 100% viable, for a culture that contains 4 x107bacterial cells per mL of liquid, which of the 10-fold serial dilutions (for example, 10-1, 10-2, 10-3, etc.) would you need to plate to obtain between 10 and 500 colonies per plate? How many colonies should appear?
