A loopful of bacteria containing 1000 bacterial cells is inoculated into a nutrient broth and incubated. After a negligible lag phase, the culture goes into exponential growth for two hours. The generation time for the bacterium is fifteen minutes. Which equation is the correct one to determine the number of cells present after two hours of log phase growth?
a. 1000 X 28
b. 1000 X 16
c. 1000 X 22
d. 1000 X 2 X 2 X 15

Explanation:

Given;

Initial population of bacteria = 1000;

exponential growth for 2 hours;

generation time = 15 minutes;

so,

Bacteria are doubling in every fifteen minute,

In staring, there are 1000 bacteria and after fifteen minutes they become 2000 and after next fifteen minutes bacteria again doubles and become 4000   and so on for next two hours.

so after 2 hours, number of cells of  bacteria present are 1000 X 2^8

Total bacterial cells after two hours= 256000.