Degrader density determines spatial variability of 2,6-dichlorobenzamide mineralisation in soil.
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.
Sjøholm
Ole Rüdiger
OR
Department of Agriculture and Ecology, Section of Genetics and Microbiology, University of Copenhagen, Thorvaldsensvej 40, 1871 Frederiksberg C, Denmark. ors@life.ku.dk
Aamand
Jens
J
Sørensen
Jan
J
Nybroe
Ole
O
D020561:Alphaproteobacteria / Q000378:metabolism; D001549:Benzamides / Q000378:metabolism*; D001673:Biodegradation, Environmental; D012988:Soil Microbiology; D012989:Soil Pollutants / Q000378:metabolism*
D001549:Benzamides; D012989:Soil Pollutants; C057454:2,6-dichlorobenzamide