Editing Genetic transformation (section)

==Definitions==
Transformation is one of three forms of [[horizontal gene transfer]] that occur in nature among bacteria, in which DNA encoding for a trait passes from one bacterium to another and is integrated into the recipient genome by [[homologous recombination]]; the other two are [[Transduction (genetics)|transduction]], carried out by means of a [[bacteriophage]], and [[bacterial conjugation|conjugation]], in which a gene is passed through direct contact between bacteria.<ref name=Johnston/> In transformation, the genetic material passes through the intervening medium, and uptake is completely dependent on the recipient bacterium.<ref name=Johnston/>

[[Competence (biology)|Competence]] refers to a temporary state of being able to take up exogenous DNA from the environment; it may be induced in a laboratory.<ref name=Johnston/>

It appears to be an ancient process inherited from a common prokaryotic ancestor that is a beneficial adaptation for promoting recombinational repair of DNA damage, especially damage acquired under stressful conditions. Natural genetic transformation appears to be an adaptation for repair of DNA damage that also generates [[genetic diversity]].<ref name=Johnston /><ref name=Michod />

Transformation has been studied in medically important [[Gram-negative bacteria]] species such as ''[[Helicobacter pylori]]'', ''[[Legionella pneumophila]]'', ''[[Neisseria meningitidis]]'', ''[[Neisseria gonorrhoeae]]'', ''[[Haemophilus influenzae]]'' and ''[[Vibrio cholerae]]''.<ref name=Seitz>{{cite journal | vauthors = Seitz P, Blokesch M | title = Cues and regulatory pathways involved in natural competence and transformation in pathogenic and environmental Gram-negative bacteria | journal = FEMS Microbiology Reviews | volume = 37 | issue = 3 | pages = 336–63 | date = May 2013 | pmid = 22928673 | doi = 10.1111/j.1574-6976.2012.00353.x | url = https://infoscience.epfl.ch/record/181130/files/fmr353.pdf | doi-access = free }}</ref>  It has also been studied in Gram-negative species found in soil such as ''[[Pseudomonas stutzeri]]'', ''Acinetobacter baylyi'', and Gram-negative [[plant pathology|plant pathogens]] such as ''[[Ralstonia solanacearum]]'' and ''[[Xylella fastidiosa]]''.<ref name=Seitz /> Transformation among [[Gram-positive bacteria]] has been studied in medically important species such as ''[[Streptococcus pneumoniae]]'', ''[[Streptococcus mutans]]'', ''[[Staphylococcus aureus]]'' and ''[[Streptococcus sanguinis]]'' and in Gram-positive soil bacterium ''[[Bacillus subtilis]]''.<ref name=Michod>{{cite journal | vauthors = Michod RE, Bernstein H, Nedelcu AM | title = Adaptive value of sex in microbial pathogens | journal = Infection, Genetics and Evolution | volume = 8 | issue = 3 | pages = 267–85 | date = May 2008 | pmid = 18295550 | doi = 10.1016/j.meegid.2008.01.002 | bibcode = 2008InfGE...8..267M }}</ref> It has also been reported in at least 30 species of ''[[Pseudomonadota]]'' distributed in several different classes.<ref name="pmid17997281">{{cite journal | vauthors = Johnsborg O, Eldholm V, Håvarstein LS | title = Natural genetic transformation: prevalence, mechanisms and function | journal = Research in Microbiology | volume = 158 | issue = 10 | pages = 767–78 | date = December 2007 | pmid = 17997281 | doi = 10.1016/j.resmic.2007.09.004 | doi-access = free }}</ref> The best studied ''Pseudomonadota'' with respect to transformation are the medically important human pathogens ''[[Neisseria gonorrhoeae]]'', ''[[Haemophilus influenzae]]'', and ''[[Helicobacter pylori]]''.<ref name=Michod/>

"Transformation" may also be used to describe the insertion of new genetic material into nonbacterial cells, including animal and plant cells; however, because "[[Malignant transformation|transformation]]" has a special meaning in relation to animal cells, indicating progression to a cancerous state, the process is usually called "[[transfection]]".<ref name=Alberts/>