Horizontal gene transfer by free DNA among bacteria in their habitat
Wackernagel, W.
Genetik, Fachbereich Biologie, Universität Oldenburg, Postfach 2503,
D-26111 Oldenburg, Germany
The active uptake of DNA into bacterial cells and the inheritable integration of the genetic information is termed natural genetic transformation. Transformation is considered to be the genuine bacterial gene transfer mechanism because the necessary functions for DNA binding, processing, uptake and recombinational assimilation are provided by chromosomally located genes. Among the roughly 50 bacterial species so far identified to be transformable are Gram-negative and Gram-positive bacteria and Archaea. Transformation can occur within a species and has also been observed between different species. Many of the transformable strains are clinical isolates of human pathogens, but a majority represents microorganisms living in the environment. It is assumed that transformation has significant impact on genetic adaptive processes and microbial evolution [1]. Aspects on transformation in natural bacterial habitats (particularly soil) are reviewed including the release of DNA from cells, the persistence of DNA in the environment, and the uptake of DNA molecules (including plasmids) even when these are
associated with solid mineral surfaces [2]. The gene-shuffling effect of transformation by plasmids within a population will be detailed. A specific note on the recently detected transformation of soil bacteria by DNA released from recombinant plants will be made with emphasis on safety considerations on the spread of recombinant DNA [3].
[1] Lorenz, M.G. and Wackernagel, W. (1994) Microbiol. Rev. 58, 563-602.
[2] Blum, S.A.E., Lorenz, M.G. and Wackernagel, W. (1997) System. Appl. Microbiol. 20, 513-521.
[3] de Vries, J. and Wackernagel, W. (1998) Molec. Gen. Genet., in press.
| LOCATION |
DATE |
TIME |
| Lecture Hall I |
Thursday, April 9 |
02:40 pm |