title: Intermediate accumulation of metabolites results in a bottleneck for mineralisation of the herbicide metabolite 2,6-dichlorobenzamide (BAM) by Aminobacter spp.
abstract: Degradation and mineralisation of the groundwater contaminant 2,6-dichloro-benzamide (BAM) was investigated in two Aminobacter strains focussing on the induction of BAM degradation and mineralisation and occurrence of intermediate metabolites. The BAM degradation rate was independent of whether the cells were pre-grown in the absence or presence of BAM, thus indicating that the first step in the degradation pathway was constitutively expressed. In contrast, (14)CO(2) production was stimulated when cells were pre-grown in the presence of BAM, suggesting that one or more of the subsequent steps in the degradation pathway were inducible. Accumulation of 2,6-dichlorobenzoate (DCBA) during degradation of BAM demonstrated that the first step involved amidase activity. Mass balance calculations and thin-layer chromatography coupled with autoradiographic detection indicated that degradation of DCBA and at least one unknown metabolite may comprise a bottleneck for BAM mineralisation by Aminobacter spp. The study thus provides novel information about the BAM degradation pathway and points to the involvement of unknown intermediate metabolites in degradation of this important groundwater contaminant.
authors: Department of Geochemistry, Geological Survey of Denmark and Greenland (GEUS), Øster Voldgade 10, 1350 Copenhagen K, Denmark.
authors: Allan
authors: A
authors: Simonsen
authors: Nora
authors: N
authors: Badawi
authors: Gitte G
authors: GG
authors: Anskjær
authors: Christian N
authors: CN
authors: Albers
authors: Sebastian R
authors: SR
authors: Sørensen
authors: Jan
authors: J
authors: Sørensen
authors: Jens
authors: J
authors: Aamand
mesh_terms: D020561:Alphaproteobacteria / Q000201:enzymology / Q000378:metabolism*; D000581:Amidohydrolases / Q000378:metabolism; D001426:Bacterial Proteins / Q000378:metabolism; D001549:Benzamides / Q000378:metabolism*; D001673:Biodegradation, Environmental; D060587:Groundwater / Q000737:chemistry; D006540:Herbicides / Q000378:metabolism*; D014874:Water Pollutants, Chemical / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D001549:Benzamides; D006540:Herbicides; D014874:Water Pollutants, Chemical; C057454:2,6-dichlorobenzamide; D000581:Amidohydrolases; C019665:amidase