Catabolism of the groundwater micropollutant 2,6-dichlorobenzamide beyond 2,6-dichlorobenzoate is plasmid encoded in Aminobacter sp. MSH1

• Published in: Applied microbiology and biotechnology Vol. 102; no. 18; pp. 7963 - 7979
• Main Authors: T’Syen, Jeroen, Raes, Bart, Horemans, Benjamin, Tassoni, Raffaella, Leroy, Baptiste, Lood, Cédric, van Noort, Vera, Lavigne, Rob, Wattiez, Ruddy, Kohler, Hans-Peter E., Springael, Dirk
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.09.2018; Springer; Springer Nature B.V
• Subjects: Acids; Amidase; Amides; Applied Genetics and Molecular Biotechnology; Biodegradation; Biomedical and Life Sciences; Biotechnology; Catabolism; Chemical properties; Contamination; Degradation; Dioxygenase; Drinking water; Environmental aspects; Genes; Genomes; Groundwater; Integrase; Life Sciences; Metabolism; Methods; Microbial Genetics and Genomics; Microbiology; Micropollutants; Observations; Oxygenase; Water sampling; Drinking water treatment; Catabolic pathway; 2,6-Dichlorobenzamide; Plasmid encoded; Aminobacter
• ISSN: 0175-7598; 1432-0614
• DOI: 10.1007/s00253-018-9189-9

Aminobacter sp. MSH1 uses the groundwater micropollutant 2,6-dichlorobenzamide (BAM) as sole source of carbon and energy. In the first step, MSH1 converts BAM to 2,6-dichlorobenzoic acid (2,6-DCBA) by means of the BbdA amidase encoded on the IncP-1 β plasmid pBAM1. Information about the genes and degradation steps involved in 2,6-DCBA metabolism in MSH1 or any other organism is currently lacking. Here, we show that the genes for 2,6-DCBA degradation in strain MSH1 reside on a second catabolic plasmid in MSH1, designated as pBAM2. The complete sequence of pBAM2 was determined revealing that it is a 53.9 kb repABC family plasmid. The 2,6-DCBA catabolic genes on pBAM2 are organized in two main clusters bordered by IS elements and integrase genes and encode putative functions like Rieske mono-/dioxygenase, meta -cleavage dioxygenase, and reductive dehalogenases. The putative mono-oxygenase encoded by the bbdD gene was shown to convert 2,6-DCBA to 3-hydroxy-2,6-dichlorobenzoate (3-OH-2,6-DCBA). 3-OH-DCBA was degraded by wild-type MSH1 and not by a pBAM2-free MSH1 variant indicating that it is a likely intermediate in the pBAM2-encoded DCBA catabolic pathway. Based on the activity of BbdD and the putative functions of the other catabolic genes on pBAM2, a metabolic pathway for BAM/2,6-DCBA in strain MSH1 was suggested.