·
Bacterial Generation Time (or) Doubling Time

1. Lag Phase

2. Exponential (or) logarithomic Phase (or) Log phase

3. Stationary phase

4. Decline Phase

**1. Lag Phase:**

·
When microorganism is introduced in to the first
medium.

·
It take some time to adjust which the new
environment.

·
Cellular metabolism is accelerated.

·
Cells are increasing in size.

·
By bacteria replicate.

**2. Exponential (or) Log phase:**

·
The microorganism rapidly growing and divided
state.

·
Organism DNA replicate begin by Binary fission
at a constant rate.

·
The time taken bacteria to double in number a
specified period is Known as the generation
time.

**3. Stationary phase:**

·
As bacteria Population continuous to growth .

·
All the nutrients in the growth medium are used
up by the microorganism for the Rapid multiplication.

·
Then reproduction rate will slow down.

·
This phase divided cells and number of cell
death rate is equal.

·
Finally stop the division completely.

**4. Decline (or) Death Phase:**

·
The bacteria completely loses its ability to
reproduce.

Ex:

E.coli ---------------------- 20 minutes

S.enterica --------------20 minutes

S.aureus -------------------30 Minutes

B.Cerus----------------------30 Minutes

Formula: 2 Number of
Generation X Intial Number of Bacteria = Total Cells

Ex :

“Bacillus subtilies “ Divided every 30 minutes, you inoculated a culture with exactly 100
Bacterial cells. After 3 hours, how many bacteria are present?

3 hours, B.subtilies Cells will Divided 6 times

Therefore,

N= 6 =26 = 2 X2 X 2X 2X 2X 2 = 64

= 64 X 100= 6400 cells