Bacteria undergo recombination using the mechanisms of transformation, conjugation and transduction. Recombination is the process of transfer of genetic material and is essential for the organism to develop and evolve. Recombination leads to gene conversion with a mutant allele becoming a wild-type or vice versa.
For recombination an organism requires two homologous DNA molecules but bacteria have only one chromosome. This makes them acquire the extra DNA molecule either from the environment, or from another bacterium or through a bacteriophage intermediate. These three processes are referred to using the terms transformation, conjugation and transduction. Transformation is when a living bacterium picks up a dead DNA remnant from a bacterium that has been destroyed. Conjugation is a sort of sexual mating with two bacteria exchanging genetic material. Transduction involves the creation of defective DNA package which cannot replicate by itself but can infect other cells and become a part of their genetic formulation.