Question

What is the generation time of a bacterial population that increases from 100 cells to 100,000 cells in 3 hours of growth?

Answer 1

In the laboratory, under favorable conditions, a growing bacterial population doubles at regular intervals. Growth is by geometric progression: 1, 2, 4, 8, etc. or 20, 21, 22, 23.........2n (where n = the number of generations). This is called exponential growth. In reality, exponential growth is only part of the bacterial life cycle, and not representative of the normal pattern of growth of bacteria in Nature.

When a fresh medium is inoculated with a given number of cells, and the population growth is monitored over a period of time, plotting the data will yield a typical bacterial growth curve (Figure 3 below).


Figure 3. The typical bacterial growth curve. When bacteria are grown in a closed system (also called a batch culture), like a test tube, the population of cells almost always exhibits these growth dynamics:  cells initially adjust to the new medium (lag phase) until they can start dividing regularly by the process of binary fission (exponential phase).  When their growth becomes limited, the cells stop dividing (stationary phase), until eventually they show loss of viability (death phase).  Note the parameters of the x and y axes.  Growth is expressed as change in the number viable cells vs time.  Generation times are calculated during the exponential phase of growth.  Time measurements are in hours for bacteria with short generation times.

Answer 2

Answer: 18 minutes

Explanation: we need to calculate first number of generations by using 3.3log N/N0. N= final cells and N0 = initial cells.

Then uu get answeer = 9.9. so now time is given 3 hours means 180 minutes.

Now generation time = t/n (t== time and n=no. 0f generations (here 9.9))

180/9.9= 18.18 hence approx is 18 minutes