1. Horizontal Gene Transfer: New Gene Acquisition
Transformation: naked DNA uptake by bacteria
Transduction: bacterial DNA transferred by viruses (phage)
Conjugation: Conjugation occurs by direct contact between two bacteria: plasmids form a mating bridge across the bacteria and DNA is exchanged, which can result in acquisition of antibiotic-resistance genes by the recipient cell. Transposons are sequences of DNA that carry their own recombination enzymes that allow for transposition from one location to another; transposons can also carry antibiotic-resistance genes.
Transformation: naked DNA is released on lysis of an organism and is taken up by another organism
Transduction: In transduction, antibiotic-resistance genes are transferred from one bacterium to another by means of bacteriophages and can be integrated into the chromosome of the recipient c
Note they are often inserted near phage/transposon genes or sites of TRNA
-Genetic diversity: metabolic properties; virulence traits; antibiotic resistance
Conjugation: DNA transfer between bacterial cells
Furuya EY and Lowy F (2006) Nat Rev Microbiol. 4: 36–45.

2. Horizontal Gene Transfer: New Gene Acquisition
Selfish mechanisms result in genetic diversity
Often confer properties of virulence, antibiotic resistance, or metabolic fitness
May provide different characteristics
Utilization of energy sources
Acid tolerance
Development of symbiosis
Ability to cause disease
Pathogenicity islands

3. Horizontal Gene Transfer: New Gene Acquisition
Lyse antibiotic resistant cells
SDS + 60˚C
Why are we using DNA that has an antibiotic resistant marker?
How are we able to lyse the cells?
DNA component with antibiotic resistance marker gets released

4. Horizontal Gene Transfer: New Gene Acquisition
Combine free DNA with cells sensitive to the antibiotic and plate on non-selective media +

5. Horizontal Gene Transfer: New Gene Acquisition
Plate transformed cells on plates selective for antibiotic resistance

6. Horizontal Gene Transfer: New Gene Acquisition
DNA only: test that it is inert/not-alive
StrS cells
StrR cells
1 loopful StrS cells. Place 1 loopful DNA ON TOP of those cells
1 loopful StrS cells.
THEN one loopful DNase
THEN one loopful DNA
b) StrS cells
c) StrR cells
d) StrS cells
+ DNA
a) DNA only
e) StrS cells
+ DNase
+ DNA