Identification of the Amidase BbdA That Initiates Biodegradation of the Groundwater Micropollutant 2,6-dichlorobenzamide (BAM) in Aminobacter sp. MSH1

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• 作者：Jeroen T鈥橲yen ; Raffaella Tassoni ; Lars Hansen ; S酶ren J. Sorensen ; Baptiste Leroy ; Aswini Sekhar ; Ruddy Wattiez ; Ren茅 De Mot ; Dirk Springael
• 刊名：Environmental Science & Technology
• 出版年：2015
• 出版时间：October 6, 2015
• 年：2015
• 卷：49
• 期：19
• 页码：11703-11713
• 全文大小：458K
• ISSN：1520-5851

文摘

2,6-dichlorobenzamide (BAM) is a recalcitrant groundwater micropollutant that poses a major problem for drinking water production in European countries. Aminobacter sp. MSH1 and related strains have the unique ability to mineralize BAM at micropollutant concentrations but no information exists on the genetics of BAM biodegradation. An amidase鈥擝bdA鈥攃onverting BAM to 2,6-dichlorobenzoic acid (DCBA) was purified from Aminobacter sp. MSH1. Heterologous expression of the corresponding bbdA gene and its absence in MSH1 mutants defective in BAM degradation, confirmed its BAM degrading function. BbdA shows low amino acid sequence identity with reported amidases and is encoded by an IncP1-尾 plasmid (pBAM1, 40.6 kb) that lacks several genes for conjugation. BbdA has a remarkably low K_M for BAM (0.71 渭M) and also shows activity against benzamide and ortho-chlorobenzamide (OBAM). Differential proteomics and transcriptional reporter analysis suggest the constitutive expression of bbdA in MSH1. Also in other BAM mineralizing Aminobacter sp. strains, bbdA and pBAM1 appear to be involved in BAM degradation. BbdA鈥檚 high affinity for BAM and its constitutive expression are of interest for using strain MSH1 in treatment of groundwater containing micropollutant concentrations of BAM for drinking water production.