Multidrug resistance is transfered among bacteria through plasmids by -
Conjugation: it is the process where by a male or donor bacterium mates or makes physical contact with a female or recepient bacterium and transfer genetic material into it. This has been considered to be the bacterial equivalent of sexual mating in higher organisms but the analogy is irrelevant as following conjugation the female bacterium is in turn conveed into male cell. Bacterial conjugation was first described by Lederberg and Tatum (1946) in a strain of E.coli called K12 and has been most extensively studied in strain. it takes place between a male cell and a female cell. The maleness or donor status of a cell is determined by the presence in it of a plasmid that coded for specialised fimbriae which project from surface of the cell.. The plasmid DNA replicate and a copy of it passes from the donor to the recepirnt attains donor status and can inturn conjugate with other female cells. The maleness in bacteria is thus a transmissible or infectious characteristic . along with plasmid DNA , poion of the host DNA also are sometimes transferred to the recepient. the donor DNA then combines with DNA of the recepient effecting genetic recombination. It was E.coli K12 that the role of plasmid in conjugation was first recognised. the plasmid responsible was termed the sex facto or feility (F)factor. When other similar similar plasmids were also discovered the term transfer factor came to be used for all such plasmids when conferred on their host cells the ability to act as donor in conjugation. REF:Ananthanarayan and Panicker's Textbook ofMicrobiology 8thEdition pg no:65
Transduction
Transversion
Conjugation
Transformation
general microbiology