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Farid Brahim Belaribi - One of the best experts on this subject based on the ideXlab platform.
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densities and excess molar volumes of the ternary system 1 4 dioxane 2 propanol 1 1 2 2 tetrachloroethane at t 288 15 318 15 k and at atmospheric pressure experimental measurements and prigogine flory patterson modeling
Journal of Chemical & Engineering Data, 2019Co-Authors: Houda Benabida, Christophe Coquelet, Farid Brahim BelaribiAbstract:Excess molar volumes for 1,4-dioxane + 2-propanol + 1,1,2,2-tetrachloroethane ternary mixture and for the constituent binaries were determined from density measurements over the entire composition ...
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densities and excess molar volumes of the ternary system 1 4 dioxane 2 propanol 1 1 2 2 tetrachloroethane at t 288 15 318 15 k and at atmospheric pressure experimental measurements and prigogine flory patterson modeling
Journal of Chemical & Engineering Data, 2019Co-Authors: Houda Benabida, Christophe Coquelet, Farid Brahim BelaribiAbstract:Excess molar volumes for 1,4-dioxane + 2-propanol + 1,1,2,2-tetrachloroethane ternary mixture and for the constituent binaries were determined from density measurements over the entire composition range at four temperatures between 288.15 and 318.15 K and at atmospheric pressure. The ether-containing binary mixtures present a positive excess molar volume, VE, with alkanol and negative VE values with chloroalkane over the whole composition and working temperature ranges. As the temperature increases, the VE magnitude increases for 1,4-dioxane + 2-propanol, whereas it decreases for 1,4-dioxane + 1,1,2,2-tetrachloroethane. For 2-propanol + 1,1,2,2-tetrachloroethane mixture, sigmoidal–VE curves are observed and the VE increases as the temperature increases. Sigmoidal–V123E curves are observed also for 1,4-dioxane + 2-propanol + 1,1,2,2-tetrachloroethane ternary mixture. The equations of Redlich–Kister and Cibulka were used to fit the experimental excess molar volume data, for the investigated binary and terna...
Julien Maillard - One of the best experts on this subject based on the ideXlab platform.
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Coexistence of two distinct Sulfurospirillum populations respiring Tetrachloroethene—genomic and kinetic considerations
FEMS Microbiology Ecology, 2018Co-Authors: Géraldine Florence Buttet, Tobias Goris, Alexandra Marie Murray, Melissa Burion, Massimo Rolle, Julien MaillardAbstract:Two anaerobic bacterial consortia, each harboring a distinct Sulfurospirillum population, were derived from a 10 year old consortium, SL2, previously characterized for the stepwise dechlorination of Tetrachloroethene (PCE) to cis-dichloroethene (cis-DCE) via accumulation of trichloroethene (TCE). Population SL2-1 dechlorinated PCE to TCE exclusively, while SL2-2 produced cis-DCE from PCE without substantial TCE accumulation. The reasons explaining the long-term coexistence of the populations were investigated. Genome sequencing revealed a novel Sulfurospirillum species, designated 'Candidatus Sulfurospirillum diekertiae', whose genome differed significantly from other Sulfurospirillum spp. (78%-83% ANI). Genome-wise, SL2-1 and SL2-2 populations are almost identical, but differences in their Tetrachloroethene reductive dehalogenase sequences explain the distinct dechlorination patterns. An extended series of batch cultures were performed at PCE concentrations of 2-200 μM. A model was developed to determine their dechlorination kinetic parameters. The affinity constant and maximal growth rate differ between the populations: the affinity is 6- to 8-fold higher and the growth rate 5-fold lower for SL2-1 than SL2-2. Mixed cultivation of the enriched populations at 6 and 30 μM PCE showed that a low PCE concentration could be the driving force for both functional diversity of reductive dehalogenases and niche specialization of organohalide-respiring bacteria with overlapping substrate ranges.
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kinetic considerations of two sulfurospirillum spp competing for Tetrachloroethene
DehaloCon II - A Conference on Anaerobic Biological Dehalogenation, 2017Co-Authors: Géraldine Florence Buttet, Alexandra Marie Murray, Melissa Burion, Julien MaillardAbstract:1 Laboratory for Environmental Biotechnology, ENAC-IIE-LBE, Ecole Polytechnique Federale de Lausanne (EPFL), Lausanne, Switzerland 2 DTU Environment, Department of Environmental Engineering, Technical University of Denmark, Lyngby, Denmark A well-established bacterial consortium that dechlorinates Tetrachloroethene (PCE) to tri- (TCE) and cis-dichloroethene (cis-DCE) in a stepwise manner has been shown to harbor two distinct populations of Sulfurospirillum spp. [1]. A genotyping method has been developed to distinguish both populations on the basis of small differences in the sequence of their respective reductive dehalogenase gene (pceA) [2]. Individual subcultures of the two Sulfurospirillum populations revealed that one of them (strain SL2-1) has a reduced dechlorination potential (PCE to TCE), while the other (SL2-2) is able to dechlorinate PCE to cis-DCE. Recent work on both the individual subcultures and the two in competition allowed investigation of the reasons for the interplay and long-term stability of both Sulfurospirillum spp. in the consortium. The kinetic parameters of PCE dechlorination were assessed for both strains by varying the PCE concentration and following growth based on chloride release and increase of the pceA gene copy number. Modelling of the data obtained revealed clear differences in affinity for PCE and maximal dechlorination rate of both strains. Moreover, inhibitory effects were observed for both populations at high PCE concentration, though it is unclear whether PCE or the dechlorination products (TCE and cis-DCE, respectively) are responsible for this. The succession of both populations in PCE and TCE dechlorination was confirmed by competition experiments at low and high PCE concentrations. We think that the obtained strain-specific kinetic parameters reflect the activity of the respective PceA enzyme, both in terms of dechlorination rate and extent. References [1] Maillard et al. (2011), Biodegradation 22:949 [2] Buttet et al. (2013), Appl Environ Microbiol 79:6941
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kinetic considerations of two sulfurospirillum spp competing for Tetrachloroethene
DehaloCon II - A Conference on Anaerobic Biological Dehalogenation, 2017Co-Authors: Géraldine Florence Buttet, Alexandra Marie Murray, Melissa Burion, Christof Holliger, Julien MaillardAbstract:1 Laboratory for Environmental Biotechnology, ENAC-IIE-LBE, Ecole Polytechnique Federale de Lausanne (EPFL), Lausanne, Switzerland 2 DTU Environment, Department of Environmental Engineering, Technical University of Denmark, Lyngby, Denmark A well-established bacterial consortium that dechlorinates Tetrachloroethene (PCE) to tri- (TCE) and cis-dichloroethene (cis-DCE) in a stepwise manner has been shown to harbor two distinct populations of Sulfurospirillum spp. [1]. A genotyping method has been developed to distinguish both populations on the basis of small differences in the sequence of their respective reductive dehalogenase gene (pceA) [2]. Individual subcultures of the two Sulfurospirillum populations revealed that one of them (strain SL2-1) has a reduced dechlorination potential (PCE to TCE), while the other (SL2-2) is able to dechlorinate PCE to cis-DCE. Recent work on both the individual subcultures and the two in competition allowed investigation of the reasons for the interplay and long-term stability of both Sulfurospirillum spp. in the consortium. The kinetic parameters of PCE dechlorination were assessed for both strains by varying the PCE concentration and following growth based on chloride release and increase of the pceA gene copy number. Modelling of the data obtained revealed clear differences in affinity for PCE and maximal dechlorination rate of both strains. Moreover, inhibitory effects were observed for both populations at high PCE concentration, though it is unclear whether PCE or the dechlorination products (TCE and cis-DCE, respectively) are responsible for this. The succession of both populations in PCE and TCE dechlorination was confirmed by competition experiments at low and high PCE concentrations. We think that the obtained strain-specific kinetic parameters reflect the activity of the respective PceA enzyme, both in terms of dechlorination rate and extent. References [1] Maillard et al. (2011), Biodegradation 22:949 [2] Buttet et al. (2013), Appl Environ Microbiol 79:6941
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functional genotyping of sulfurospirillum spp in mixed cultures allowed the identification of a new Tetrachloroethene reductive dehalogenase
Applied and Environmental Microbiology, 2013Co-Authors: Géraldine Florence Buttet, Julien MaillardAbstract: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 PceATCE, 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 sequence-substrate relationships within Tetrachloroethene reductive dehalogenases are also discussed.
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Reductive dechlorination of Tetrachloroethene by a stepwise catalysis of different organohalide respiring bacteria and reductive dehalogenases
Biodegradation, 2011Co-Authors: Julien Maillard, Marie-paule Charnay, Christophe Regeard, Emmanuelle Rohrbach-brandt, Katia Rouzeau-szynalski, Pierre RossiAbstract:The enrichment culture SL2 dechlorinating Tetrachloroethene (PCE) to ethene with strong trichloroethene (TCE) accumulation prior to cis-1,2-dichloroethene (cis-DCE) formation was analyzed for the presence of organohalide respiring bacteria and reductive dehalogenase genes (rdhA). Sulfurospirillum-affiliated bacteria were identified to be involved in PCE dechlorination to cis-DCE whereas “Dehalococcoides”-affiliated bacteria mainly dechlorinated cis-DCE to ethene. Two rdhA genes highly similar to Tetrachloroethene reductive dehalogenase genes (pceA) of S. multivorans and S. halorespirans were present as well as an rdhA gene very similar to the trichloroethene reductive dehalogenase gene (tceA) of “Dehalococcoides ethenogenes” strain 195. A single strand conformation polymorphism (SSCP) method was developed allowing the simultaneous detection of the three rdhA genes and the estimation of their abundance. SSCP analysis of different SL2 cultures showed that one pceA gene was expressed during PCE dechlorination whereas the second was expressed during TCE dechlorination. The tceA gene was involved in cis-DCE dechlorination to ethene. Analysis of the internal transcribed spacer region between the 16S and 23S rRNA genes revealed two distinct sequences originating from Sulfurospirillum suggesting that two Sulfurospirillum populations were present in SL2. Whether each Sulfurospirillum population was catalyzing a different dechlorination step could however not be elucidated.
Houda Benabida - One of the best experts on this subject based on the ideXlab platform.
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densities and excess molar volumes of the ternary system 1 4 dioxane 2 propanol 1 1 2 2 tetrachloroethane at t 288 15 318 15 k and at atmospheric pressure experimental measurements and prigogine flory patterson modeling
Journal of Chemical & Engineering Data, 2019Co-Authors: Houda Benabida, Christophe Coquelet, Farid Brahim BelaribiAbstract:Excess molar volumes for 1,4-dioxane + 2-propanol + 1,1,2,2-tetrachloroethane ternary mixture and for the constituent binaries were determined from density measurements over the entire composition ...
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densities and excess molar volumes of the ternary system 1 4 dioxane 2 propanol 1 1 2 2 tetrachloroethane at t 288 15 318 15 k and at atmospheric pressure experimental measurements and prigogine flory patterson modeling
Journal of Chemical & Engineering Data, 2019Co-Authors: Houda Benabida, Christophe Coquelet, Farid Brahim BelaribiAbstract:Excess molar volumes for 1,4-dioxane + 2-propanol + 1,1,2,2-tetrachloroethane ternary mixture and for the constituent binaries were determined from density measurements over the entire composition range at four temperatures between 288.15 and 318.15 K and at atmospheric pressure. The ether-containing binary mixtures present a positive excess molar volume, VE, with alkanol and negative VE values with chloroalkane over the whole composition and working temperature ranges. As the temperature increases, the VE magnitude increases for 1,4-dioxane + 2-propanol, whereas it decreases for 1,4-dioxane + 1,1,2,2-tetrachloroethane. For 2-propanol + 1,1,2,2-tetrachloroethane mixture, sigmoidal–VE curves are observed and the VE increases as the temperature increases. Sigmoidal–V123E curves are observed also for 1,4-dioxane + 2-propanol + 1,1,2,2-tetrachloroethane ternary mixture. The equations of Redlich–Kister and Cibulka were used to fit the experimental excess molar volume data, for the investigated binary and terna...
Géraldine Florence Buttet - One of the best experts on this subject based on the ideXlab platform.
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Coexistence of two distinct Sulfurospirillum populations respiring Tetrachloroethene—genomic and kinetic considerations
FEMS Microbiology Ecology, 2018Co-Authors: Géraldine Florence Buttet, Tobias Goris, Alexandra Marie Murray, Melissa Burion, Massimo Rolle, Julien MaillardAbstract:Two anaerobic bacterial consortia, each harboring a distinct Sulfurospirillum population, were derived from a 10 year old consortium, SL2, previously characterized for the stepwise dechlorination of Tetrachloroethene (PCE) to cis-dichloroethene (cis-DCE) via accumulation of trichloroethene (TCE). Population SL2-1 dechlorinated PCE to TCE exclusively, while SL2-2 produced cis-DCE from PCE without substantial TCE accumulation. The reasons explaining the long-term coexistence of the populations were investigated. Genome sequencing revealed a novel Sulfurospirillum species, designated 'Candidatus Sulfurospirillum diekertiae', whose genome differed significantly from other Sulfurospirillum spp. (78%-83% ANI). Genome-wise, SL2-1 and SL2-2 populations are almost identical, but differences in their Tetrachloroethene reductive dehalogenase sequences explain the distinct dechlorination patterns. An extended series of batch cultures were performed at PCE concentrations of 2-200 μM. A model was developed to determine their dechlorination kinetic parameters. The affinity constant and maximal growth rate differ between the populations: the affinity is 6- to 8-fold higher and the growth rate 5-fold lower for SL2-1 than SL2-2. Mixed cultivation of the enriched populations at 6 and 30 μM PCE showed that a low PCE concentration could be the driving force for both functional diversity of reductive dehalogenases and niche specialization of organohalide-respiring bacteria with overlapping substrate ranges.
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kinetic considerations of two sulfurospirillum spp competing for Tetrachloroethene
DehaloCon II - A Conference on Anaerobic Biological Dehalogenation, 2017Co-Authors: Géraldine Florence Buttet, Alexandra Marie Murray, Melissa Burion, Julien MaillardAbstract:1 Laboratory for Environmental Biotechnology, ENAC-IIE-LBE, Ecole Polytechnique Federale de Lausanne (EPFL), Lausanne, Switzerland 2 DTU Environment, Department of Environmental Engineering, Technical University of Denmark, Lyngby, Denmark A well-established bacterial consortium that dechlorinates Tetrachloroethene (PCE) to tri- (TCE) and cis-dichloroethene (cis-DCE) in a stepwise manner has been shown to harbor two distinct populations of Sulfurospirillum spp. [1]. A genotyping method has been developed to distinguish both populations on the basis of small differences in the sequence of their respective reductive dehalogenase gene (pceA) [2]. Individual subcultures of the two Sulfurospirillum populations revealed that one of them (strain SL2-1) has a reduced dechlorination potential (PCE to TCE), while the other (SL2-2) is able to dechlorinate PCE to cis-DCE. Recent work on both the individual subcultures and the two in competition allowed investigation of the reasons for the interplay and long-term stability of both Sulfurospirillum spp. in the consortium. The kinetic parameters of PCE dechlorination were assessed for both strains by varying the PCE concentration and following growth based on chloride release and increase of the pceA gene copy number. Modelling of the data obtained revealed clear differences in affinity for PCE and maximal dechlorination rate of both strains. Moreover, inhibitory effects were observed for both populations at high PCE concentration, though it is unclear whether PCE or the dechlorination products (TCE and cis-DCE, respectively) are responsible for this. The succession of both populations in PCE and TCE dechlorination was confirmed by competition experiments at low and high PCE concentrations. We think that the obtained strain-specific kinetic parameters reflect the activity of the respective PceA enzyme, both in terms of dechlorination rate and extent. References [1] Maillard et al. (2011), Biodegradation 22:949 [2] Buttet et al. (2013), Appl Environ Microbiol 79:6941
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kinetic considerations of two sulfurospirillum spp competing for Tetrachloroethene
DehaloCon II - A Conference on Anaerobic Biological Dehalogenation, 2017Co-Authors: Géraldine Florence Buttet, Alexandra Marie Murray, Melissa Burion, Christof Holliger, Julien MaillardAbstract:1 Laboratory for Environmental Biotechnology, ENAC-IIE-LBE, Ecole Polytechnique Federale de Lausanne (EPFL), Lausanne, Switzerland 2 DTU Environment, Department of Environmental Engineering, Technical University of Denmark, Lyngby, Denmark A well-established bacterial consortium that dechlorinates Tetrachloroethene (PCE) to tri- (TCE) and cis-dichloroethene (cis-DCE) in a stepwise manner has been shown to harbor two distinct populations of Sulfurospirillum spp. [1]. A genotyping method has been developed to distinguish both populations on the basis of small differences in the sequence of their respective reductive dehalogenase gene (pceA) [2]. Individual subcultures of the two Sulfurospirillum populations revealed that one of them (strain SL2-1) has a reduced dechlorination potential (PCE to TCE), while the other (SL2-2) is able to dechlorinate PCE to cis-DCE. Recent work on both the individual subcultures and the two in competition allowed investigation of the reasons for the interplay and long-term stability of both Sulfurospirillum spp. in the consortium. The kinetic parameters of PCE dechlorination were assessed for both strains by varying the PCE concentration and following growth based on chloride release and increase of the pceA gene copy number. Modelling of the data obtained revealed clear differences in affinity for PCE and maximal dechlorination rate of both strains. Moreover, inhibitory effects were observed for both populations at high PCE concentration, though it is unclear whether PCE or the dechlorination products (TCE and cis-DCE, respectively) are responsible for this. The succession of both populations in PCE and TCE dechlorination was confirmed by competition experiments at low and high PCE concentrations. We think that the obtained strain-specific kinetic parameters reflect the activity of the respective PceA enzyme, both in terms of dechlorination rate and extent. References [1] Maillard et al. (2011), Biodegradation 22:949 [2] Buttet et al. (2013), Appl Environ Microbiol 79:6941
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competition of two sulfurospirillum populations for Tetrachloroethene
Swiss Society of Microbiology, 2016Co-Authors: Géraldine Florence ButtetAbstract:Tetrachloroethene (PCE) represents a major groundwater pollutant. Some bacteria are able to use PCE as electron acceptor in an anaerobic respiration process called organohalide respiration (OHR). An anaerobic enrichment culture (named SL2-PCEb) consisting of two different Sulfurospirillum populations was obtained from a fixed-bed bioreactor sludge treating PCE-contaminated groundwater (1). The peculiarity of this bacterial consortium resides in stepwise dechlorination of PCE to trichloroethene (TCE) and cis-dichloroethene (cis-DCE), which is catalyzed by the two populations successively (2). Two subcultures were derived from SL2-PCEb, each one harboring one Sulfurospirillum population and showing distinct dechlorination potential: SL2-PCEc dechlorinates PCE to TCE only, while SL2-TCE (selected on TCE) kept the potential to dechlorinate both PCE and TCE. A molecular fingerprinting method targeting small differences in their rdhA genes was developed to follow the dynamics of both populations. The dechlorination activity of both populations suggested that the RdhA enzyme produced by SL2-PCEc has a higher turnover rate than the one produced by SL2-TCE (3). The present work proposes to study the competition of both SL2-PCEc and SL2-TCE populations for PCE by mixing them with different proportions and following their growth and activity. To this purpose, a new experimental set-up was developed by combining quantitative PCR and fragment analysis. This should highlight the physiological and molecular basis of the two RdhA enzymes for substrate affinity and enzymatic activity.
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competition of two sulfurospirillum populations for Tetrachloroethene
Swiss Society of Microbiology, 2016Co-Authors: Géraldine Florence ButtetAbstract:Tetrachloroethene (PCE) represents a major groundwater pollutant. Some bacteria are able to use PCE as electron acceptor in an anaerobic respiration process called organohalide respiration (OHR). An anaerobic enrichment culture (named SL2-PCEb) consisting of two different Sulfurospirillum populations was obtained from a fixed-bed bioreactor sludge treating PCE-contaminated groundwater (1). The peculiarity of this bacterial consortium resides in stepwise dechlorination of PCE to trichloroethene (TCE) and cis-dichloroethene (cis-DCE), which is catalyzed by the two populations successively (2). Two subcultures were derived from SL2-PCEb, each one harboring one Sulfurospirillum population and showing distinct dechlorination potential: SL2-PCEc dechlorinates PCE to TCE only, while SL2-TCE (selected on TCE) kept the potential to dechlorinate both PCE and TCE. A molecular fingerprinting method targeting small differences in their rdhA genes was developed to follow the dynamics of both populations. The dechlorination activity of both populations suggested that the RdhA enzyme produced by SL2-PCEc has a higher turnover rate than the one produced by SL2-TCE (3). The present work proposes to study the competition of both SL2-PCEc and SL2-TCE populations for PCE by mixing them with different proportions and following their growth and activity. To this purpose, a new experimental set-up was developed by combining quantitative PCR and fragment analysis. This should highlight the physiological and molecular basis of the two RdhA enzymes for substrate affinity and enzymatic activity.
Christophe Coquelet - One of the best experts on this subject based on the ideXlab platform.
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densities and excess molar volumes of the ternary system 1 4 dioxane 2 propanol 1 1 2 2 tetrachloroethane at t 288 15 318 15 k and at atmospheric pressure experimental measurements and prigogine flory patterson modeling
Journal of Chemical & Engineering Data, 2019Co-Authors: Houda Benabida, Christophe Coquelet, Farid Brahim BelaribiAbstract:Excess molar volumes for 1,4-dioxane + 2-propanol + 1,1,2,2-tetrachloroethane ternary mixture and for the constituent binaries were determined from density measurements over the entire composition ...
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densities and excess molar volumes of the ternary system 1 4 dioxane 2 propanol 1 1 2 2 tetrachloroethane at t 288 15 318 15 k and at atmospheric pressure experimental measurements and prigogine flory patterson modeling
Journal of Chemical & Engineering Data, 2019Co-Authors: Houda Benabida, Christophe Coquelet, Farid Brahim BelaribiAbstract:Excess molar volumes for 1,4-dioxane + 2-propanol + 1,1,2,2-tetrachloroethane ternary mixture and for the constituent binaries were determined from density measurements over the entire composition range at four temperatures between 288.15 and 318.15 K and at atmospheric pressure. The ether-containing binary mixtures present a positive excess molar volume, VE, with alkanol and negative VE values with chloroalkane over the whole composition and working temperature ranges. As the temperature increases, the VE magnitude increases for 1,4-dioxane + 2-propanol, whereas it decreases for 1,4-dioxane + 1,1,2,2-tetrachloroethane. For 2-propanol + 1,1,2,2-tetrachloroethane mixture, sigmoidal–VE curves are observed and the VE increases as the temperature increases. Sigmoidal–V123E curves are observed also for 1,4-dioxane + 2-propanol + 1,1,2,2-tetrachloroethane ternary mixture. The equations of Redlich–Kister and Cibulka were used to fit the experimental excess molar volume data, for the investigated binary and terna...
