Most bacteria normally exist and reproduce by asexual means in haploid state. As a result of genetic transfer, a diploid state can arise transiently but full diploid state is rarely attained.
Genetic transfer in bacteria takes occurs by unidirectional passage of DNA from the donor cell to the recipient cell. This can be achieved in three ways:
Conjugation: It is a form of gene transfer and recombination that requires direct cell to cell contact.
Transformation: In this type of transfer, the piece of free DNA is taken up by the bacterial cell and integrated into the recipient's genome.
Transduction: Exchange of DNA takes place by means of bacteriophages.