PG AND RESEARCH DEPARTMENT OF MICROBIOLOGY,SRI PARAMAKALYANI COLLEGE ALWARKURUCHI-627 412

2. Synopsis
◦ Bacterial Growth
◦ Binary fission
1. Steps involved in binary fission
2. types of binary fission
◦ Generation time
◦ Examples
◦ Reference

3. BACTERIAL GROWTH
◦ The growth is defined as an increase in number of microbial
cell in a population which can be measured as an increased
cell mass.
◦ Therefore, bacteria increase their numbers by geometric
progression whereby their population doubles every
generation time.
◦ Bacterial growth involves the asexual reproduction of the
organism, in which the bacterium undergoes binary fission
to divide into two daughter cells.

4. BINARY FISSION
◦ Fission, in biology, is the division of a single entity into
two or more parts and the regeneration of those parts to
separate entities resembling the original.
◦ Bacteria and archaea most commonly engage in a process
known as binary fission. Other, less common processes can
include multiple fission, budding, and the production of
spores.
◦ The fission may be binary fission, in which a single
organism produces two parts, or multiple fission, in which
a single entity produces multiple parts.

5. The steps involved in the binary fission in bacteria
are:
◦ Step 1- Replication of DNA
The bacterium uncoils and
replicates its chromosome,
essentially doubling its content.
◦ Step 2- Growth of a Cell
After copying the chromosome,
the bacterium starts to grow
larger in preparation for binary
fissions.

6. It is followed by an increase in cytoplasmic content.
Another prominent trait of this stage is that the two
strands migrate to opposite poles of the cell.
◦ Step 3-Segregation of DNA
The cell elongates with a septum forming at the middle.
The two chromosomes are also separated in this phase.
◦ Step 4- Splitting of Cells
A new cell wall is formed at this phase, and the cell
splits at the centre, dividing the parent cell into two new
daughter cells. Each of the daughter cells contains a copy
of the nuclear materials as necessary organelles.

7. Cell division by binary fission

8. Types of Binary Fission
◦ Irregular binary fission – This is the type of binary
fission in which cytokinesis (the division of the cytoplasm)
occurs along a plane perpendicular to that of Karyokinesis.
Here, the plane of cytokinesis is always perpendicular to
plane on which Karyokinesis occurred.
◦ Longitudinal binary fission – This is the type of mitosis in
which fission/cytokinesis occurs along a longitudinal axis.
◦ Transverse binary fission – In this type of binary fission,
cytokinesis occurs along the transverse axis.

9. Types of binary fission

10. GENERATION TIME
◦ The time interval for the formation of two daughter cell
from one is called generation time or doubling time.
◦ Generation time vary widely among organism.
◦ Under optimal condition, generation time determines the
rate of microbial growth.
◦ The growth can be quantitatively analyzed by the
determination of generation time. Therefore, generation
time is a unit to measure bacterial growth.
◦ Let suppose, No is the initial population of certain
bacteria.

11. ◦ The population of bacteria after 1 generation (N1)= 2 x
No.
◦ The number of cells increases exponentially and can be
expressed as 2n, where n is the number of generations.
◦ In our example, we used one cell as the initial number of
cells. For any number of starting cells, the formula is
adapted as follows:
Nn=N0 * 2n
Nn is the number of cells at any generation n, N0 is the
initial number of cells, and n is the number of generations.

12. The parental cell divides and gives rise to two daughter cells.
Each of the daughter cells, in turn, divides, giving a total of four
cells in the second generation and eight cells in the third
generation. Each division doubles the number of cells.

13. Examples of organisms that use Binary Fission
◦ Organisms that reproduce by binary fission include
Bacillus subtilis, B. cereus, B. pumilus, Escherichia coli,
Clostridium perfringens, Corynebacterium diphtheriae,
etc.
◦ In protozoans like amoeba, Paramecium, Euglena, however,
the process might differ in cell splitting and in how the
cytoplasm divides.

14. Reference
◦ https://microbiologyclass.com/microbial-growth-doubling-
time-and-binary-fission/
◦ https://open.oregonstate.education/generalmicrobiology/chap
ter/microbial-growth/
◦ https://bio.libretexts.org/Bookshelves/Microbiology/Book%3
A_Microbiology_(Kaiser)/Unit_7%3A_Microbial_Genetics_and
_Microbial_Metabolism/17%3A_Bacterial_Growth_and_Energ
y_Production/17.1%3A_Bacterial_Growth
◦ https://www.onlinebiologynotes.com/bacterial-growth-curve/
◦ https://slideplayer.com/amp/10678501/

17. Skills improvement by taking seminar
◦ Confidence Level
◦ Fearlessness
◦ Self motivation
◦ Assertiveness