The large-scale release of wild-type or genetically modified bacteria into the environment for control of @entity66 or for bioremediation entails the potential risk of groundwater contamination by these microorganisms. For a model study on patterns of vertical transport of bacteria under field conditions, the biocontrol strain @entity11763 CHA0, marked with a spontaneous resistance to @entity1215 (CHA0-Rif), was applied to a grass-clover ley plot (rotation grassland) and a @entity3505 plot. Immediately after bacterial application, heavy precipitation was simulated by sprinkling, over a period of 8 h, 40 mm of water containing the mobile tracer @entity27801 and the dye Brilliant Blue FCF to identify channels of preferential flow. One day later, a 150-cm-deep soil trench was dug and soil profiles were prepared. Soil samples were extracted at different depths of the profiles and analyzed for the number of CHA0-Rif cells and the concentration of @entity4001 and @entity28912 . Dye coverage in the soil profiles was estimated by image analysis. CHA0 was present at 10(sup8) CFU/g in the surface soil, and 10(sup6) to 10(sup7) CFU/g of CHA0 was detected along macropores between 10 and 150 cm deep. Similarly, the concentration of the tracer @entity4001 along the macropores remained at the same level below 20 cm deep. Dye coverage in lower soil layers was higher in the ley than in the @entity3505 plot. In nonstained parts of the profiles, the number of CHA0-Rif cells was substantially smaller and the @entity4001 concentration was below the detection limit in most samples. We conclude that after heavy rainfall, released bacteria are rapidly transported in large numbers through the channels of preferential flow to deeper soil layers. Under these conditions, the transport of CHA0-Rif is similar to that of the conservative tracer @entity4001 and is affected by cultural practice.

Importance of Preferential Flow and Soil Management in Vertical Transport of a Biocontrol Strain of XXXX in Structured Field Soil.

@entity28912 :: ('MESH:C006796', 'Chemical') :: ['Brilliant Blue FCF'] @entity66 :: ('MESH:D004194', 'Disease') :: ['plant diseases'] @entity11763 :: ('294', 'Species') :: ['Pseudomonas fluorescens'] @entity27801 :: ('MESH:C039004', 'Chemical') :: ['potassium bromide'] @entity1215 :: ('MESH:D012293', 'Chemical') :: ['rifampin'] @entity3505 :: ('4565', 'Species') :: ['wheat'] @entity4001 :: ('CHEBI:15858', 'Chemical') :: ['bromide']
@entity11763 :: (294,Species) :: ['Pseudomonas fluorescens']
