Studies on Gene Flux by Free Bacterial DNA in Soil, Sediment and Groundwater Aquifer

Abstract

The presence of extracellular high molecular weight DNA in sedimentary and aqueous environments (DeFlaun et al., 1987; Ogram et al., 1987) and the fact that many bacterial species present in these environments can develop natural competence for DNA uptake (Lorenz and Wackernagel, 1988) has raised the question whether horizontal gene transfer by genetic transformation occurs in these habitats. Following several initial studies which suggested a relatively high DNA stability in the evironment (Greaves and Wilson, 1970; Lorenz et al., 1981; Aardema et al., 1983; Lorenz and Wackernagel, 1987; Romanowski et al., 1991) this topic has received increasing attention. Genetic transformation in natural habitats would have profound impacts on biological and ecological aspects of bacterial life including evolution, population dynamics and spread of genetic material not normally part of bacterial genomes. With respect to safety considerations about the deliberate or accidental release of genetically-modified microorganisms a gene flux by bacterial dissemination of free DNA would be of special importance.