A 0.1 ml sample of a log phase culture contains 10,000 bacterial cells/ml. It is added to 9.9 ml of fresh culture medium broth. Assume a generation time of 30 minutes, and no limiting nutrients. How many bacteria will be present in the entire broth culture after five hours?
A) 3.2 × 10⁴
B) 5.0 × 10⁵
C) 1.02 × 10⁶
D) 6.0 × 10⁶
E) 2.56 × 10⁷

Question

Quizplus · Accepted Answer

First, we need to calculate the number of generations that will occur in 5 hours.

5 hours = 300 minutes 
Generation time = 30 minutes

Number of generations = 300/30 = 10

Next, we can use the formula:

N = N₀ x 2ⁿ

where N₀ is the initial number of bacteria, n is the number of generations, and N is the final number of bacteria.

N₀ = 10,000

n = 10

N = 10,000 x 2¹⁰ = 10,000 x 1,024 = 10,240,000

However, we added the initial 0.1 ml to 9.9 ml of fresh medium, giving us a total volume of 10 ml.

So, the bacterial concentration will be:

10,240,000 / 10 = 1,024,000

Therefore, the answer is C) 1.02 × 10⁶.

A 01 Ml Sample of a Log Phase Culture Contains 10,000