Bacterial Growth and Multiplication-Microbiology|ICDS supervisor Exam Kerala PSC
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Bacterial Growth and Multiplication |
Bacterial Growth and Multiplication
Bacterial growth refers to the increase in the no. of individual cell.
Normally bacteria reproduce by Binary Fission.
Asexual reproduction
is a separation of a body into two new bodies in the process of a
binary fission.
Organisms duplicates its genetic material and then
divides into two parts with each new organism receiving one copy of
DNA .
A few bacterial species also reproduce by Budding.
Budding is
formation of small initial outgrowth which is called Bud then it
enlarges until its size approaches to the parent cell and then it
separate.
Generation Time
The time required for a cell to divide (and its population to double) is called the
generation time.
E. coli under favorable conditions double in 20 minutes and Mycobacterium in 24hours.
Logarithmic Representation of Bacterial Populations
Phases of Growth
When a few bacteria are inoculated into a liquid growth medium and the
population is counted at intervals, it is possible to plot a bacterial growth
curve that shows the growth of cells over time.
There are four basic phases of
growth:
The lag, log, stationary, and death phases.
1.The Lag Phase
This period of little or no cell division is called the lag phase, and it can last for
1 hour or several days depending upon the species of bacteria.
The microbial
population is undergoing a period of intense metabolic activity involving, in
particular, synthesis of enzymes and various molecules.
2. The Log Phase
In this phase the cells begin to divide and enter a period of growth, or
logarithmic increase, called the log phase, or exponential growth phase.
Cellular reproduction is most active during this period, and generation time
reaches a constant minimum.
Because the generation time is constant, a
logarithmic plot of growth during the log phase is a straight line.
The log phase
is the time when cells are most active metabolically and is preferred for
industrial purposes where, for
example, a product needs to be
produced efficiently.
3. The Stationary Phase
If exponential growth continued
unchecked, startlingly large
numbers of cells could arise but
in reality this does not happen.
In
this phase the growth rate slow
down the number of microbial
deaths balances the number of
new cells, and the population
stabilizes.
The metabolic activity
of individual cell serving also
slows down at this stage.
4. The Death Phase
The number of deaths eventually exceeds the number of new cells formed, and
the population enters the death phase, or logarithmic decline phase.
This
phase continues until the population is diminished to a tiny fraction of the
number of cells as compared to the previous phase or until the population dies
out entirely.
Many bacterial cells often undergoes involution during this phase
meaning that their morphology changes dramatically & make them difficult to
identify.
Also Read;
Morphology of Bacteria
Anatomy of Bacteria
Vaccination -Types
This topic is important for the ICDS Supervisor Exam.Click HERE.
You can Go to more posts Regarding ICDS Supervisor Kerala PSC Here.
More ICDS Supervisor Kerala PSCSociology Notes Here
ICDS Supervisor Kerala PSC Homescience Notes Here
Microbiology Notes
ICDS Supervisor Kerala PSC Food ,Nutrition and Health Notes Here
Also Read;
Morphology of Bacteria
Anatomy of Bacteria
Vaccination -Types
This topic is important for the ICDS Supervisor Exam.Click HERE.
You can Go to more posts Regarding ICDS Supervisor Kerala PSC Here.
More ICDS Supervisor Kerala PSCSociology Notes Here
ICDS Supervisor Kerala PSC Homescience Notes Here
Microbiology Notes
ICDS Supervisor Kerala PSC Food ,Nutrition and Health Notes Here
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