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6 September 2019

Bacterial Growth and Multiplication-Microbiology|ICDS supervisor Exam Kerala PSC

Bacterial Growth and Multiplication-Microbiology|ICDS supervisor Exam Kerala PSC

Bacterial Growth and Multiplication

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

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