Reductive dechlorination of tetrachloroethene by a stepwise catalysis of different organohalide respiring bacteria and reductive dehalogenases

Maillard, Julien; Charnay, Marie-Paule; Regeard, Christophe; Rohrbach-Brandt, Emmanuelle; Rouzeau-Szynalski, Katia; Rossi, Pierre; Holliger, Christof

doi:10.1007/s10532-011-9454-4

Cited by 26 publications

(36 citation statements)

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“…In this work, several consortia were investigated which were previously selected from the SL2 consortium, which was established from a fixed-bed bioreactor treating groundwater pumped to the surface from a PCE-contaminated site (29,30). Both pure isolates Sulfurospirillum multivorans DSM 12446 and S. halorespirans DSM 13726 were obtained from the DSMZ culture collection (DSMZ, Braunschweig, Germany).…”

Section: Methodsmentioning

confidence: 99%

“…The SL2 consortium was considered a model of an OHR consortium degrading PCE completely to ethene and were shown to contain members of the genera Sulfurospirillum and Dehalococcoides (29,30). Sulfurospirillum spp.…”

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confidence: 99%

“…Sulfurospirillum spp. were demonstrated to catalyze the first two steps of dechlorination (from PCE to cis-DCE), whereas members of the genus Dehalococcoides were involved in the final steps (from cis-DCE to ethene) (30), with the most striking feature being a clear stepwise dechlorination process. The succession of different enzymes and/or bacterial populations along the dechlorination pattern was then proposed but could not be demonstrated clearly.…”

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confidence: 99%

“…A new consortium, SL2-PCEb, was selected from SL2 by serial dilutions and frequent culture transfers when trichloroethene (TCE) dechlorination was almost complete (30). This consortium had lost the ability to dechlorinate cis-DCE and was shown to contain only Sulfurospirillum spp.…”

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confidence: 99%

“…It was still characterized by a strong transient TCE accumulation, further suggesting that at least two Sulfurospirillum populations were maintained in SL2-PCEb. Initial identification and detection of rdhA genes by single-strand conformation polymorphism (SSCP) analysis revealed the presence of several gene fragments showing strong similarity to type 1 and type 2 rdhA genes of Sulfurospirillum isolates and suggested the involvement of the former enzymes in the stepwise dechlorination of PCE to cis-DCE (30). However, neither analysis of 16S rRNA genes nor that of the internal transcribed spacer region allowed a clear distinction of multiple Sulfurospirillum populations.…”

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confidence: 99%

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Functional Genotyping of Sulfurospirillum spp. in Mixed Cultures Allowed the Identification of a New Tetrachloroethene Reductive Dehalogenase

Buttet

Holliger

Maillard

2013

Appl Environ Microbiol

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Reductive dehalogenases are the key enzymes involved in the anaerobic respiration of organohalides such as the widespread groundwater pollutant tetrachloroethene. The increasing number of available bacterial genomes and metagenomes gives access to hundreds of new putative reductive dehalogenase genes that display a high level of sequence diversity and for which substrate prediction remains very challenging. In this study, we present the development of a functional genotyping method targeting the diverse reductive dehalogenases present in Sulfurospirillum spp., which allowed us to unambiguously identify a new reductive dehalogenase from our tetrachloroethene-dechlorinating SL2 bacterial consortia. The new enzyme, named PceA TCE , shows 92% sequence identity with the well-characterized PceA enzyme of Sulfurospirillum multivorans, but in contrast to the latter, it is restricted to tetrachloroethene as a substrate. Its apparent higher dechlorinating activity with tetrachloroethene likely allowed its selection and maintenance in the bacterial consortia among other enzymes showing broader substrate ranges. The sequencesubstrate relationships within tetrachloroethene reductive dehalogenases are also discussed. Widespread use of chlorinated solvents in cleaning and metaldegreasing operations over the last century has resulted in extensive environmental contamination by chlorinated ethenes. Tetrachloroethene (PCE) is currently one of the main contaminants of aquifers. Different remediation strategies have been developed, including bioremediation, which uses microorganisms for the degradation of pollutants (1). Several genera of strictly anaerobic bacteria, including Desulfitobacterium (2), Dehalococcoides (3), Dehalobacter (4), and Sulfurospirillum (5), are able to conserve energy via the reductive dehalogenation of chloroethenes by a respiratory metabolism (6-9) recently coined organohalide respiration (OHR). The enzyme class involved in OHR for the reduction of halogenated compounds is known as the reductive dehalogenase (RdhA) family (10, 11). Most RdhA enzymes have been isolated from OHR bacteria (OHRB) as 48-to 65-kDa monomers consisting of a single polypeptide chain and containing one corrinoid cofactor and two iron-sulfur clusters. The majority of currently known OHRB carry multiple rdhA genes, i.e., 1 to 36 genes, depending on the strain (12). Several studies have demonstrated that the presence of multiple nonidentical rdhA genes is a typical feature of OHRB (13-15). This suggests that the substrate range of the OHRB may be far greater than previously believed (16). However, substrate specificity has been determined for only about 15 enzymes within the several hundreds of putative rdhA sequences reported in databases (12). Moreover, transcriptomic studies on strains displaying multiple rdhA genes often failed to clearly identify which reductive dehalogenase was responsible for the dechlorination of specific substrates (12,(17)(18)(19)(20).The genus Sulfurospirillum comprises microaerophilic or facultative anaerob...

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