The exchange of Genetic
Material between bacteria
or
How bacteria acquire resistance to
antimicrobial agents in nature
Modes of genetic exchange
transformation
phage mediated transduction
conjugation
transposition
Transformation of bacteria with
linear DNA—some cells are naturally
competent for the uptake of DNA
Plasmids are
autonomously
replicating
circular DNA
molecules that can be
used to artificially
transform bacteria—
naturally competent
cells can take up a
plasmid, such plasmid
does not need to
integrate with the
chromosome for
maintenance!!
Generalized transduction
mediated by bacteriophages
Conjugation
—a
mechanism
by which
mobilizable
plasmids
can be
transferred
from one
bacterium
to another
Note tra genes, oriT and antibiotic resisitance genes
Conjugation—a mechanism by which
mobilizable plasmids can be transferred
from one bacterium to another
Note conjugation bridge formed between donor and recipient cells
Mobilizable
plasmids can
integrate into
the bacterial
chromosome
—therefore
bacterial
genes can be
transferred.
Transposons that carry antibiotic
resistance genes can randomly “hop”
into a bacterial chromosome
Mechanism for transposition
ABR
ABR