1. By
SWETHA MOHAN.S
I-Msc., Microbiology
TRANSDUCTION

2. DEFINITION:
 The transfer of genetic material from one cell to
another cell by a bacteriophage is called
Transduction.
 Transduction has been found to occur in variety of
prokaryotes , including certain species of Bacteria :
e.g: Escherichia , Pseudomonas,
Salmonella , Staphylococcus , etc.
 The bacteriophage containing the bacterial DNA is
called transduced DNA .

3. Transduction was first discovered by
Norton Zinder and Joshua Lederberg in 1952.
Joshua LederbergNorton Zinder
History:

4.  Studied in Salmonella typhimurium
 Plated two auxotrophic strains (LA-2 and LA-
22) individually on minimal medium, no cells
grew.
 Plated a mixture of the two auxotrophic
strains on minimal medium, cells grew into
colonies.
 Thus, genetic exchange was taking place
between two cell types.

5. U-Tube Experiment

6. Types of Bacteriophage:
 VIRULENT : Capable of causing infection eventually
destruction and death of the bacterial cell . These follow
LYTIC CYCLE .
Example : T4 host E.coli .
 TEMPERATE: Does not cause destruptic infection instead
phage DNA incorporated into bacterial DNA and replicate
(LYSOGENIC)and after some cycle become virulent cause
lysis.
Example : lamda phage .

7. There are TWO types of transduction
1. Generalized transduction
A DNA fragment is transferred from
one bacterium to another by a lytic
bacteriophage(virulent) which carrying donor
•
bacterial DNA due to an error .
• 2. Specialized transduction
A DNA fragment is transferred from
one bacterium to another by a temperate
bacteriophage which carrying donor DNA along
with phage genome due to an error .In this a
phage insert a genome at specific site.
TYPES OF TRANSDUCTION:

8. Generalized:
 Transduction in which potentially any donor genes
can be transferred.

9. GENERALIZED
TRANSDUCTION:
Infect the host cell
The bacteriophage genome enters
the bacterium.

10. Bacteriophage (carries a host DNA)
attach to the recipient cell

11. The bacteriophage inserts the donor
bacterium's DNA it is carrying into the
recipient bacterium .
The donor bacterium”s DNA
exchange the some of the recipient
bacterium”s DNA

12. EXAMPLE:

13. Specialized:
 Transduction in which only certain donor genes can
be transferred.

14. SPECIALIZED TRANSDUCTION:
A temperate bacteriophage attach to
the host cell and inject there genome
The bacteriophage inserts its
genome into the bacterium's nucleoid
to become a prophage.

15. Occasionally during spontaneous
induction, a small piece of the donor
bacterium's DNA is picked up as part of the
phage's genome in place of some of the phage
DNA which remains in the bacterium's
nucleoid.
As the bacteriophage replicates, the
segment of bacterial DNA replicates as part of
the phage's genome. Every phage now carries
that segment of bacterial DNA.

16. The bacteriophage genome carrying the
donor bacterial DNA
inserts into the recipient bacterium's
nucleoid.
The bacteriophage adsorbs to a recipient
bacterium and injects
its genome.

18. Significance of transduction:
 It transfers genetic material from one bacterial cell
to another and alter the genetic characteristics.
 For example: In specialized transduction the gal
gene, a cell lacking ability to metabolize galactose
could aquire the ability .
 It shows the evolutionary relationship between the
prophage and host bacterial cell.
 Prophage can exist in a cell for a long period
suggests a similar possible mechanism for the viral
origin of cancer.
 It provides a way to study the gene linkage.

19. THANK YOU