<P> Transformation is one of three processes for horizontal gene transfer, in which exogenous genetic material passes from bacterium to another, the other two being conjugation (transfer of genetic material between two bacterial cells in direct contact) and transduction (injection of foreign DNA by a bacteriophage virus into the host bacterium). In transformation, the genetic material passes through the intervening medium, and uptake is completely dependent on the recipient bacterium . </P> <P> As of 2014 about 80 species of bacteria were known to be capable of transformation, about evenly divided between Gram - positive and Gram - negative bacteria; the number might be an overestimate since several of the reports are supported by single papers . 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 . It has also been studied in gram - negative species found in soil such as Pseudomonas stutzeri, Acinetobacter baylyi, and gram - negative plant pathogens such as Ralstonia solanacearum and Xylella fastidiosa . </P> <Table> <Tr> <Td> </Td> <Td> This section needs additional citations for verification . Please help improve this article by adding citations to reliable sources . Unsourced material may be challenged and removed . (April 2013) (Learn how and when to remove this template message) </Td> </Tr> </Table> <Tr> <Td> </Td> <Td> This section needs additional citations for verification . Please help improve this article by adding citations to reliable sources . Unsourced material may be challenged and removed . (April 2013) (Learn how and when to remove this template message) </Td> </Tr>

Where do gram negative bacteria live in the body