Environ. Biosafety Res.
Volume 6, Number 1-2, January-June 2007Thematic Issue on Horizontal Gene Transfer
|Page(s)||37 - 53|
|Published online||12 September 2007|
Release and persistence of extracellular DNA in the environment
Department of Pharmacy, Faculty of Medicine, University of Tromsø,
9037 Tromsø, Norway
2 Norwegian Institute of Gene Ecology, 9294 Tromsø, Norway
3 Faculty of Life Sciences, University of Manchester, Manchester, M13 9PT, UK
4 Department of Food Science, Technology and Microbiology, University of Milan, Via Celoria 2, 20133 Milan, Italy
Corresponding author: email@example.com
The introduction of genetically modified organisms (GMOs) has called for an improved understanding of the fate of DNA in various environments, because extracellular DNA may also be important for transferring genetic information between individuals and species. Accumulating nucleotide sequence data suggest that acquisition of foreign DNA by horizontal gene transfer (HGT) is of considerable importance in bacterial evolution. The uptake of extracellular DNA by natural transformation is one of several ways bacteria can acquire new genetic information given sufficient size, concentration and integrity of the DNA. We review studies on the release, breakdown and persistence of bacterial and plant DNA in soil, sediment and water, with a focus on the accessibility of the extracellular nucleic acids as substrate for competent bacteria. DNA fragments often persist over time in many environments, thereby facilitating their detection and characterization. Nevertheless, the long-term physical persistence of DNA fragments of limited size observed by PCR and Southern hybridization often contrasts with the short-term availability of extracellular DNA to competent bacteria studied in microcosms. The main factors leading to breakdown of extracellular DNA are presented. There is a need for improved methods for accurately determining the degradation routes and the persistence, integrity and potential for horizontal transfer of DNA released from various organisms throughout their lifecycles.
Key words: DNA release, stability, persistence or degradation / biosafety / GMO / lateral or horizontal gene transfer / natural transformation
© ISBR, EDP Sciences, 2007