Dispersal of plasmid pJP4 in unsaturated and saturated 2,4-dichlorophenoxyacetic acid contaminated soil

Little is known regarding plasmid fate within contaminated soils. Column studies were used to evaluate dissemination of plasmid pJP4 under unsaturated or saturated flow conditions in a 2,4-dichlorophenoxyacetic acid (2,4-D) contaminated soil. Columns were destructively sampled following 1 week of percolation to assess the vertical distribution of donors, transconjugants, and 2,4-D concentrations within the soil. In unsaturated soil, pJP4 was detected in both culturable donor and transconjugant cells within soil 10.5 cm from the inoculated end of the column. In saturated soil, no transconjugants were detected; however, donors were found throughout the entire length of the column (30.5 cm). These results suggest that donor transport, particularly in conjunction with plasmid transfer to indigenous recipients, allows for significant dispersal of introduced genes through contaminated soil.