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

Note conjugation bridge formed between donor and recipient cells

Conjugation—a mechanism by which mobilizable plasmids can be transferred

from one bacterium to another

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