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1. A gourmet chef inoculated a delicious potato salad with 6 Staphylococcus aure

ID: 39258 • Letter: 1

Question

1. A gourmet chef inoculated a delicious potato salad with 6 Staphylococcus aureus cells. If S. aureushas a generation time of 60 minutes, how many cells would be in the culture after 10 hours.

2. Use the dilution scheme shown below and answer the questions that follow. 1.0 mL

Original Sample

0.1 mL 0.1 mL 0.1 mL 1.0 mL 1.0 mL

9.0 mL 0.9 mL 9.9 mL 9.9 mL 9.0 mL 9.0 mL

I II III IV V VI

0.1 mL

0.1 ml

48 colonies

50 colonies

Calculate

1. The dilution of each tube in the series
2. The approximate concentration of viable cells in the original culture.
3. Suppose that the original sample had a concentration of 1.0 x 1010 cells/mL. Based on the latter

concentration, how many cells are in tubes I, II, III, IV, V, and VI?

Explanation / Answer

Answer-- 1) 128 cells would be in the culture after 10 hours.