Mobility of the organochlorine compound dicofol in soil promoted by Pseudomonas fluorescens

The genetic modified Pseudomonas fluorescens Br 12, resistant to kanamycin and rifampycin, was used to follow the cotransport of the organochlorine ac aricide dicofol through a nonsterilized soil column. P, fluorescens was fou nd to bioaccumulate dicofol with the highest bioconcentration factor of 279 within 30 min. Separate soil column experiments where applied P, fluoresce ns or [C-14]dicofol were submitted to heavy rain simulation did not reveal any correlation between the distribution patterns of P, fluorescens and [C- 14]dicofol in the leachate fractions (r = 0.3). Similar experiments with P. fluorescens that previously had bioaccumulated [C-14]dicofol demonstrated a high correlation of these bacteria and radioactivity in the leachate frac tions (r = 0.8). The total recovery of radioactivity in the leachate, when [C-14]dicofol was previously bioaccumulated in bacteria, was more than two times higher (4.5%) than the total recovery of radioactivity in the leachat e when [C-14] dicofol was directly applied in the soil (2%), This indicates cotransport by Pseudomonas. Fractionation and analysis of soil columns ind icated that most of the bioaccumulated dicofol was rapidly released and ads orbed in soil, while bacteria moved down by leaching. (C) 1999 Academic Pre ss.