Image: Janice Haney Carr/CDC
Bacteria propagate or reproduce most commonly by a kind of cell division called binary fission. In binary fission, a single cell divides and two identical cells are formed. This is an effective way for bacteria to reproduce, however it does produce problems. Since the cells produced through this type of reproduction are identical, they are all susceptible to the same types of antibiotics.
In order to incorporate some genetic variation, bacteria undergo a process called recombination. Bacterial recombination can be accomplished through conjugation, transformation, or transduction. In conjugation, bacteria transfer pieces of their genes to other bacteria through a protein tube structure called a pilus. In transformation, bacteria take up DNA from their environment and incorporate it into their own DNA. In transduction, bacterial DNA is exchanged through a type of virus that infects bacteria called a bacteriophage.