Degradation of trace concentrations of the persistent groundwater pollutant 2,6-dichlorobenzamide (BAM) in bioaugmented rapid sand filters

Albers, Christian Nyrop; Feld, Louise; Ellegaard-Jensen, Lea; Aamand, Jens

doi:10.1016/j.watres.2015.06.023

Cited by 79 publications

(93 citation statements)

References 32 publications

(28 reference statements)

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“…Filter material was sampled from the top of the sand filter using a spoon rinsed with ethanol. Samples from the middle of the filter were taken using a custom-made pipe system (11). Samples of filter material were brought to the laboratory and immediately processed for most-probable-number (MPN) analysis of phenoxypropionate degraders.…”

Section: Methodsmentioning

confidence: 99%

“…Coextraction of DNA and RNA from freeze-dried samples was done using a PowerMicrobiome RNA isolation kit (catalog no. 26000-50; MO BIO Laboratories, Inc., Carlsbad, CA, USA) with a modified procedure as previously described (11). The extracted RNA was immediately converted to cDNA using, first, an RTS DNase kit (MO BIO Laboratories) and, subsequently, a RevertAid Premium RT kit in combination with random hexamer primers (Thermo Scientific, Inc., Lithuania) for reverse transcription-PCR, according to the manufacturers' instructions.…”

Section: Methodsmentioning

confidence: 99%

“…As an alternative, pesticide-contaminated water may be remediated by passing the water through a sand filter with degrading bacteria. Recently, we observed the potential for the remediation of groundwater polluted by the pesticide residue 2,6-dichlorobenzamide (BAM) in a sand filter bioaugmented with specific BAM-degrading bacteria (11). Laboratory-scale sand filters with sand and bacteria from a fullscale waterworks similarly removed various organic chemicals, including the pesticides 2,4-dichlorophenoxyacetic acid (2,4-D), aldicarb, chlorpyrifos, and diazinon (12).…”

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Establishment of Bacterial Herbicide Degraders in a Rapid Sand Filter for Bioremediation of Phenoxypropionate-Polluted Groundwater

Feld

Nielsen

Hansen

et al. 2016

Appl Environ Microbiol

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In this study, we investigated the establishment of natural bacterial degraders in a sand filter treating groundwater contaminated with the phenoxypropionate herbicides (RS)-2-(4-chloro-2-methylphenoxy)propanoic acid (MCPP) and (RS)-2-(2,4-dichlorophenoxy)propanoic acid (DCPP) and the associated impurity/catabolite 4-chlorophenoxypropanoic acid (4-CPP). A pilot facility was set up in a contaminated landfill site. Anaerobic groundwater was pumped up and passed through an aeration basin and subsequently through a rapid sand filter, which is characterized by a short residence time of the water in the filter. For 3 months, the degradation of DCPP, MCPP, and 4-CPP in the sand filter increased to 15 to 30% of the inlet concentration. A significant selection for natural bacterial herbicide degraders also occurred in the sand filter. Using a most-probable-number (MPN) method, we found a steady increase in the number of culturable phenoxypropionate degraders, reaching approximately 5 ؋ 10 5 degraders per g sand by the end of the study. Using a quantitative PCR targeting the two phenoxypropionate degradation genes, rdpA and sdpA, encoding stereospecific dioxygenases, a parallel increase was observed, but with the gene copy numbers being about 2 to 3 log units higher than the MPN. In general, the sdpA gene was more abundant than the rdpA gene, and the establishment of a significant population of bacteria harboring sdpA occurred faster than the establishment of an rdpA gene-carrying population. The identities of the specific herbicide degraders in the sand filter were assessed by Illumina MiSeq sequencing of 16S rRNA genes from sand filter samples and from selected MPN plate wells. We propose a list of potential degrader bacteria involved in herbicide degradation, including representatives belonging to the Comamonadaceae and Sphingomonadales.G roundwater is a valuable resource that is used for drinking water in many countries all over the world. The quality of the water is vital to our health, and regulations have been made to control the concentration of contaminants and protect the groundwater (1). A major concern is leaching of pesticides mainly from agricultural areas but also from urban areas or from point sources (2). In the European Union, a legal threshold limit has been set at 0.1 g/liter for any given pesticide or 0.5 g/liter for a total concentration of mixed pesticides in drinking water (3).In Denmark, monitoring of the groundwater status has detected pesticides in almost 40% of the investigated wells, and the concentrations exceed the allowed threshold limit in 12% of the wells (4). Phenoxypropionate herbicides, including the compounds (RS)-2-(2,4-dichlorophenoxy)propanoic acid (known as DCPP or dichlorprop) and (RS)-2-(4-chloro-2-methylphenoxy)propanoic acid (known as MCPP or mecoprop), are among the pesticides frequently found in contaminated wells (4). The herbicides are, in particular, a problem in old landfill areas, from where they are leaching into the groundwater as a point source contamination (5). Phe...

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 99%

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Establishment of Bacterial Herbicide Degraders in a Rapid Sand Filter for Bioremediation of Phenoxypropionate-Polluted Groundwater

Feld

Nielsen

Hansen

et al. 2016

Appl Environ Microbiol

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“…Aminobacter sp. strain MSH1 is an aerobic soil isolate that mineralizes BAM and uses the compound as C, N, and energy sources (2,9). The organism was proposed as a candidate biological catalyst for bioaugmentation of dedicated filtration units in DWTPs to treat BAM-contaminated intake water (8).…”

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confidence: 99%

“…A similar reduction in specific BAM-degrading activity was found in a DWTP pilot-scale sand filter study that investigated bioaugmentation with Aminobacter sp. MSH1 for treating BAM-contaminated groundwater (9). An often-observed feature of organic-xenobioticdegrading bacteria that might contribute to reduced activity is the instability of the genes encoding pollutant catabolism.…”

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Genetic (In)stability of 2,6-Dichlorobenzamide Catabolism in Aminobacter sp. Strain MSH1 Biofilms under Carbon Starvation Conditions

Horemans

Raes

Brocatus

et al. 2017

Appl Environ Microbiol

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Aminobacter sp. strain MSH1 grows on and mineralizes the groundwater micropollutant 2,6-dichlorobenzamide (BAM) and is of interest for BAM removal in drinking water treatment plants (DWTPs). The BAM-catabolic genes in MSH1 are located on plasmid pBAM1, carrying bbdA, which encodes the conversion of BAM to 2,6-dichlorobenzoic acid (2,6-DCBA) (BbdA ϩ phenotype), and plasmid pBAM2, carrying gene clusters encoding the conversion of 2,6-DCBA to tricarboxylic acid (TCA) cycle intermediates (Dcba ϩ phenotype). There are indications that MSH1 easily loses its BAM-catabolic phenotype. We obtained evidence that MSH1 rapidly develops a population that lacks the ability to mineralize BAM when grown on nonselective (R2B medium) and semiselective (R2B medium with BAM) media. Lack of mineralization was explained by loss of the Dcba ϩ phenotype and corresponding genes. The ecological significance of this instability for the use of MSH1 for BAM removal in the oligotrophic environment of DWTPs was explored in lab and pilot systems. A higher incidence of BbdA ϩ Dcba Ϫ MSH1 cells was also observed when MSH1 was grown as a biofilm in flow chambers under C and N starvation conditions due to growth on nonselective residual assimilable organic carbon. Similar observations were made in experiments with a pilot sand filter reactor bioaugmented with MSH1. BAM conversion to 2,6-DCBA was not affected by loss of the DCBA-catabolic genes. Our results show that MSH1 is prone to BAM-catabolic instability under the conditions occurring in a DWTP. While conversion of BAM to 2,6-DCBA remains unaffected, BAM mineralization activity is at risk, and monitoring of metabolites is warranted.IMPORTANCE Bioaugmentation of dedicated biofiltration units with bacterial strains that grow on and mineralize micropollutants was suggested as an alternative for treating micropollutant-contaminated water in drinking water treatment plants (DWTPs). Organic-pollutant-catabolic genes in bacteria are often easily lost, especially under nonselective conditions, which affects the bioaugmentation success. In this study, we provide evidence that Aminobacter sp. strain MSH1, which uses the common groundwater micropollutant 2,6-dichlorobenzamide (BAM) as a C source, shows a high frequency of loss of its BAM-mineralizing phenotype due to the loss of genes that convert 2,6-DCBA to Krebs cycle intermediates when nonselective conditions occur. Moreover, we show that catabolic-gene loss also occurs in the oligotrophic environment of DWTPs, where growth of MSH1 depends mainly on the high fluxes of low concentrations of assimilable organic carbon, and hence show the ecological relevance of catabolic instability for using strain MSH1 for BAM removal in DWTPs.

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Combining bioadsorption and photoelectrochemical oxidation for the treatment of soil‐washing effluents polluted with herbicide 2,4‐D

Chair

Boutarfaïa

Bensalah

et al. 2016

J of Chemical Tech & Biotech

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Degradation of trace concentrations of the persistent groundwater pollutant 2,6-dichlorobenzamide (BAM) in bioaugmented rapid sand filters

Cited by 79 publications

References 32 publications

Establishment of Bacterial Herbicide Degraders in a Rapid Sand Filter for Bioremediation of Phenoxypropionate-Polluted Groundwater

Establishment of Bacterial Herbicide Degraders in a Rapid Sand Filter for Bioremediation of Phenoxypropionate-Polluted Groundwater

Genetic (In)stability of 2,6-Dichlorobenzamide Catabolism in Aminobacter sp. Strain MSH1 Biofilms under Carbon Starvation Conditions

Combining bioadsorption and photoelectrochemical oxidation for the treatment of soil‐washing effluents polluted with herbicide 2,4‐D

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