Question

A food worker was preparing some macaroni salad on the same counter on which he had cut up some raw chicken. Suppose this resulted in the accidental introduction of 380 cells of E. coli into the 1 gallon container of macaroni. This careless worker then left it unrefrigerated until 6 hours later. Now consider that E. coli has a doubling (generation) time of 20 minutes when grown in a rich medium. Assuming the cells were dividing at their maximum rate in the macaroni salad, what would the level of bacterial contamination be by the time it was finally refrigerated?

Answer 1

Answer:

99,614,720 cells

Explanation:

Since the population of E. coli doubles every 20 minutes, and one hour has three sets of 20 minutes, then six hours have 18 sets of 20 minutes or 18 generation lapses. In order to calculate the final rate of infection we need to calculate 18 doublings of the initial population of 380 cells, which equals to 99,614,720 cells.