Degrader density determines spatial variability of 2,6-dichlorobenzamide mineralisation in soil.

Ole Rüdiger Sjøholm, Jens Aamand, Jan Sørensen, Ole Nybroe

Department of Agriculture and Ecology, Section of Genetics and Microbiology, University of Copenhagen, Thorvaldsensvej 40, 1871 Frederiksberg C, Denmark. ors@life.ku.dk

Environmental pollution (Barking, Essex : 1987) 2010 Jan

filter terms:

The metabolite 2,6-dichlorobenzamide (BAM) is a frequent groundwater pollutant produced during degradation of the herbicide 2,6-dichlorobenzonitrile (dichlobenile). Spatial variability of BAM mineralisation is uncharacterized in surface soil, however, and factors controlling the heterogeneity remain unknown. We addressed these issues by sample-to-sample comparisons of BAM mineralisation rates and a range of soil characteristics at spatial scales ranging from meters to centimetres. For mineralisation assays nano-molar concentrations of labelled BAM were added to determine mineralisation rates under realistic conditions. We found a significant variability of BAM mineralisation which increased with decreasing spatial scale. BAM mineralisation rates were correlated to the density of BAM-degrading bacteria but not to water content, TOC, NH(4)(+), NO(3)(-), or pH. The genus Aminobacter, which contains the only BAM degraders known, was detected in MPN samples of BAM degraders by a specific PCR assay targeting the 16S rRNA gene, confirming a role of Aminobacter in BAM mineralisation.

Citation

Ole Rüdiger Sjøholm, Jens Aamand, Jan Sørensen, Ole Nybroe. Degrader density determines spatial variability of 2,6-dichlorobenzamide mineralisation in soil. Environmental pollution (Barking, Essex : 1987). 2010 Jan;158(1):292-8