Bacteria have a life cycle that includes four phases: lag phase, log or exponential phase, stationary phase, and death or decline phase. During the lag phase, bacteria adjust to their environment but do not grow. In the log phase, bacteria multiply rapidly through cell division. The stationary phase occurs when growth limiting factors like nutrient depletion cause growth to dwindle. Finally, in the death phase bacteria die off faster than new cells are produced as nutrients are exhausted.

1. LIFE CYCLE Of BACTERIA
A bacteria is an unicellular organism whose normal
work is that causing diseases by its rapid growth.

2. Here we see about the life
cycle of a bacteria
There are some basic needs for a bacteria to grow in a
medium.
(ie., to multiply)

3. Energy source,and a source of carbon and other required nutrients,
and some physical conditions such as o2 conc.,temp,and ph,moisture
based on their patterns of growth under various chemical
(nutritional) or physical conditions.
For example
phototrophs are organisms that use light as an energy
source;
anaerobes are organisms that grow without oxygen;
thermophiles are organisms that grow at high temperatures.

4. According to these conditions they can grow. The
growth is measured in a graph.
The growth curve has 4 phases:
Lag phase
Log or exponential phase
Stationary phase
Death or decline phase

5. Growth curve

6. Lag phase
A Bacteria do not grow during the lag phase. They
do adjust to their environment and metabolize, that
is, produce vitamins and amino acids needed for
division. They begin making copies of their DNA,
and if the environment supplies plenty of nutrients,
the lag phase may be very short. Then the bacteria
will proceed to the next phase of their life. This
phase occurs slowly.

7. Log phase
During the log phase, bacteria multiply rapidly,
even exponentially. The time it takes for a culture to
double is called "generation time," and under the
best conditions, the fastest bacteria can double in
about 15 minutes. Other bacteria take days.
Metabolic activity and some physiological characteristics
were done much more fastly.

8. The generation time g (the time required for the
population to double) can be determined from the
number of generations n that occur in a particular
time interval t the generation time is calculated by
the formula:
g= t/n=t/3.3(log10N-log10N0)
It is for e.coli because e.coli is a basic bacteria.
Not all bacteria have the same generation time.

9. During exponential growth, the growth rate
(ie., the generations per hour), termed as R is
the reciprocal of the generation time g.
R=3.3 (log10N-log10No)/t

10. Stationary phase:
During this phase bacteria growth dwindles. It is
due to some growth-limiting factor such as the
depletion of an essential nutrient, or the formation
of an inhibitory product (organic acid). This results
in a “smooth,” horizontal linear part of the curve
during the stationary phase.
The population remains constant.

11. Death phase:
With the exhaustion of nutrients and build-up of
waste and secondary metabolic products, the
growth rate has slowed to the point where the
growth rate equals the death rate. Effectively, there
is no net growth.
The bacteria may die faster than new cells
produced.