Identification of the amidase BbdA that initiates biodegradation of the groundwater micropollutant 2,6-dichlorobenzamide (BAM) in Aminobacter sp. MSH1

TY - JOUR

T1 - Identification of the amidase BbdA that initiates biodegradation of the groundwater micropollutant 2,6-dichlorobenzamide (BAM) in Aminobacter sp. MSH1

AU - T'Syen, Jeroen

AU - Tassoni, Raffaella

AU - Hansen, Lars H.

AU - Sørensen, Søren Johannes

AU - Leroy, Baptiste

AU - Sekhar, Aswini

AU - Wattiez, Ruddy

AU - De Mot, René

AU - Springael, Dirk

PY - 2015/8/26

Y1 - 2015/8/26

N2 - 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-BbdA-converting 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-β plasmid (pBAM1, 40.6 kb) that lacks several genes for conjugation. BbdA has a remarkably low KM for BAM (0.71 μM) 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's 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.

AB - 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-BbdA-converting 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-β plasmid (pBAM1, 40.6 kb) that lacks several genes for conjugation. BbdA has a remarkably low KM for BAM (0.71 μM) 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's 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.

U2 - 10.1021/acs.est.5b02309

DO - 10.1021/acs.est.5b02309

M3 - Journal article

C2 - 26308673

SN - 0013-936X

VL - 49

SP - 11703

EP - 11713

JO - Environmental Science & Technology (Washington)

JF - Environmental Science & Technology (Washington)

IS - 19

ER -