| reductive dehalogenation as a respiratory process. | anaerobic bacteria can reductively dehalogenate aliphatic and aromatic halogenated compounds in a respiratory process. only a few of these bacteria have been isolated in pure cultures. however, long acclimation periods, substrate specificity, high dehalogenation rates, and the possibility to enrich for the dehalogenation activity by subcultivation in media containing an electron donor indicate that many of the reductive dehalogenations in the environment are catalyzed by specific bacteria. molec ... | 1994 | 7747935 |
| the proton/electron ration of the menaquinone-dependent electron transport from dihydrogen to tetrachloroethene in "dehalobacter restrictus". | in the anaerobic respiration chain of "dehalobacter restrictus," dihydrogen functioned as the electron donor and tetrachloroethene (pce) functioned as the electron acceptor. the hydrogenase faced the periplasm, and the pce reductase faced the cytoplasmic side of the membrane. both activities were associated with the cytoplasmic membrane. uv spectroscopy showed that membrane-bound menaquinone (mq) was reduced by oxidation of h2 and reoxidized by reduction of pce, indicating that mq functions as a ... | 1996 | 8636034 |
| isolation of an anaerobic bacterium which reductively dechlorinates tetrachloroethene and trichloroethene. | strain tea, a strictly anaerobic, motile rod with one to four lateral flagella and a crystalline surface layer was isolated from a mixed culture that completely reduces chlorinated ethenes to ethene. the organism coupled reductive dehalogenation of tetrachloroethene or trichloroethene to cis-1,2-dichloroethene to growth, using molecular hydrogen as the electron donor. it was unable to grow fermentatively or in the presence of tri- or tetrachloroethene with glucose, pyruvate, lactate, acetate or ... | 1996 | 9188197 |
| redox chemistry of cobalamin and iron-sulfur cofactors in the tetrachloroethene reductase of dehalobacter restrictus. | respiration of dehalobacter restrictus is based on reductive dechlorination of tetrachloroethene. the terminal component of the respiratory chain is the membrane-bound tetrachloroethene reductase. the metal prosthetic groups of the purified enzyme have been studied by optical and epr spectroscopy. the 60-kda monomer contains one cobalamin with em(co[1+/2+]) = -350 mv and em(co[2+/3+]) > 150 mv and two electron-transferring [4fe-4s](2+;1+) clusters with rather low redox potentials of em approxima ... | 1997 | 9224702 |
| dehalobacter restrictus gen. nov. and sp. nov., a strictly anaerobic bacterium that reductively dechlorinates tetra- and trichloroethene in an anaerobic respiration. | the highly enriched anaerobic bacterium that couples the reductive dechlorination of tetrachloroethene to growth, previously referred to as per-k23, was obtained in pure culture and characterized. the bacterium, which does not form spores, is a small, gram-negative rod with one lateral flagellum. it utilized only h2 as an electron donor and tetrachloroethene and trichloroethene as electron acceptors in an anaerobic respiration process; it could not grow fermentatively. acetate served as a carbon ... | 1998 | 9531632 |
| phylogenetic analysis of an anaerobic, trichlorobenzene-transforming microbial consortium. | a culture-independent phylogenetic survey for an anaerobic trichlorobenzene-transforming microbial community was carried out. small-subunit rrna genes were pcr amplified from community dna by using primers specific for bacteria or euryarchaeota and were subsequently cloned. application of a new hybridization-based screening approach revealed 51 bacterial clone families, one of which was closely related to dechlorinating dehalobacter species. several clone sequences clustered to rdna sequences ob ... | 1999 | 9872791 |
| reductive dechlorination of tetrachloroethene to cis-1, 2-dichloroethene by a thermophilic anaerobic enrichment culture. | thermophilic anaerobic biodegradation of tetrachloroethene (pce) was investigated with various inocula from geothermal and nongeothermal areas. only polluted harbor sediment resulted in a stable enrichment culture that converted pce via trichloroethene to cis-1, 2-dichloroethene at the optimum temperature of 60 to 65 degrees c. after several transfers, methanogens were eliminated from the culture. dechlorination was supported by lactate, pyruvate, fructose, fumarate, and malate as electron donor ... | 1999 | 10347007 |
| tetrachloroethene-dehalogenating bacteria. | tetrachloroethene is a frequent groundwater contaminant often persisting in the subsurface environments. it is recalcitrant under aerobic conditions because it is in a highly oxidized state and is not readily susceptible to oxidation. nevertheless, at least 15 organisms from different metabolic groups, viz. halorespirators (9), acetogens (2), methanogens (3) and facultative anaerobes (2), that are able to metabolize tetrachloroethene have been isolated as axenic cultures to-date. some of these o ... | 1999 | 10664879 |
| bacteria of an anaerobic 1,2-dichloropropane-dechlorinating mixed culture are phylogenetically related to those of other anaerobic dechlorinating consortia. | a 16s-rdna-based molecular study was performed to determine the bacterial diversity of an anaerobic, 1,2-dichloropropane-dechlorinating bioreactor consortium derived from sediment of the river saale, germany. total community dna was extracted and bacterial 16s rrna genes were subsequently amplified using conserved primers. a clone library was constructed and analysed by sequencing the 16s rdna inserts of randomly chosen clones followed by dot blot hybridization with labelled polynucleotide probe ... | 2000 | 10939657 |
| development of primers for amplifying genes encoding cpra- and pcea-like reductive dehalogenases in anaerobic microbial consortia, dechlorinating trichlorobenzene and 1,2-dichloropropane. | gene sequence alignments of the reductive dehalogenases pcea (dehalospirillum multivorans) and cpra (desulfitobacterium dehalogenans) were used to develop specific pcr primers binding to conserved regions of these sequences. these primers enabled us to amplify and subsequently sequence cpra-like gene fragments from the chlororespiring species dehalobacter restrictus, desulfitobacterium sp. strain pce1, and d. hafniense. no specific amplicons were obtained from the chlororespiring species d. frap ... | 2001 | 11295458 |
| natural attenuation of chlorinated solvents at area 6, dover air force base: characterization of microbial community structure. | a polyphasic approach based on cultivation and direct recovery of 16s rrna gene sequences was utilized for microbial characterization of an aquifer contaminated with chlorinated ethenes. this work was conducted in order to support the evaluation of natural attenuation of chlorinated ethenes in groundwater at area 6 at dover air force base (dover, de). results from these studies demonstrated the aquifer contained relatively low biomass (e.g. direct microscopic counts of < 10(7) bacteria/g of sedi ... | 2002 | 12143992 |
| microbial dehalorespiration with 1,1,1-trichloroethane. | 1,1,1-trichloroethane (tca) is a ubiquitous environmental pollutant because of its widespread use as an industrial solvent, its improper disposal, and its substantial emission to the atmosphere. we report the isolation of an anaerobic bacterium, strain tca1, that reductively dechlorinates tca to 1,1-dichloroethane and chloroethane. strain tca1 required h2 as an electron donor and tca as an electron acceptor for growth, indicating that dechlorination is a respiratory process. phylogenetic analysi ... | 2002 | 12411705 |
| kinetic and phylogenetic characterization of an anaerobic dechlorinating microbial community. | the reductive dechlorination (rd) of tetrachloroethene (pce) to vinyl chloride (vc) and, to a lesser extent, to ethene (eth) by an anaerobic microbial community has been investigated by studying the processes and kinetics of the main physiological components of the consortium. molecular hydrogen, produced by methanol-utilizing acetogens, was the electron donor for the pce rd to vc and eth without forming any appreciable amount of other chlorinated intermediates and in the near absence of methano ... | 2003 | 12624208 |
| characterization of the corrinoid iron-sulfur protein tetrachloroethene reductive dehalogenase of dehalobacter restrictus. | the membrane-bound tetrachloroethene reductive dehalogenase (pce-rdase) (pcea; ec 1.97.1.8), the terminal component of the respiratory chain of dehalobacter restrictus, was purified 25-fold to apparent electrophoretic homogeneity. sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed a single band with an apparent molecular mass of 60 +/- 1 kda, whereas the native molecular mass was 71 +/- 8 kda according to size exclusion chromatography in the presence of the detergent octyl-beta-d ... | 2003 | 12902251 |
| development of degenerate and specific pcr primers for the detection and isolation of known and putative chloroethene reductive dehalogenase genes. | degenerate and specific pcr primers were designed for the detection of chloroethene reductive dehalogenases (ce-rdase), the key enzymes of chloroethene dehalorespiration, based on sequence information of three ce-rdases and three chlorophenol (cp) rdases. for the design of the degenerate primers, seven conserved amino-acid blocks identified with different bioinformatic tools were used. for one block degenerate, primers containing a 5'-consensus clamp region specific for ce-rdases and a 3'-end de ... | 2004 | 14706755 |
| development of a real-time pcr method for quantification of the three genera dehalobacter, dehalococcoides, and desulfitobacterium in microbial communities. | we developed standard curves based on plasmids containing a 16s rrna gene of a member of one of the three genera dehalobacter, desulfitobacterium, and dehalococcoides. a large difference in amplification efficiency between the standard curves was observed ranging from 1.5 to 2.0. the total eubacterial 16s rrna gene copy number determined in a sample dna by using eubacterial primers and the three standard curves led to differences in the estimated copy numbers of a factor up to 73. however, the a ... | 2004 | 15134884 |
| hydrogen threshold concentrations in pure cultures of halorespiring bacteria and at a site polluted with chlorinated ethenes. | halorespiring microorganisms are not only able to oxidize organic electron donors such as formate, acetate, pyruvate and lactate, but also h(2). because these microorganisms have a high affinity for h(2), this may be the most important electron donor for halorespiration in the environment. we have studied the role of h(2)-threshold concentrations in pure halorespiring cultures and compared them with mixed cultures and field data. we have found h(2)-threshold values between 0.05 and 0.08 nm for s ... | 2004 | 15142253 |
| regulation of anaerobic dehalorespiration by the transcriptional activator cprk. | desulfomonile, desulfitobacterium, and dehalobacter are anaerobic microbes that can derive energy from the reductive dehalogenation of chlorinated organic compounds, many of which are environmental pollutants. there is very little information about how anaerobic dehalorespiration is regulated. an open reading frame within the desulfitobacterium dehalogenans chlorophenol reductase (cpr) gene cluster (cprk) was proposed to be a transcriptional regulatory protein (smidt, h., van leest, m., van der ... | 2004 | 15381694 |
| isolation and characterization of tn-dha1, a transposon containing the tetrachloroethene reductive dehalogenase of desulfitobacterium hafniense strain tce1. | a new 9.9 kb catabolic transposon, tn-dha1, containing the gene responsible for tetrachloroethene (pce) reductive dechlorination activity, was isolated from desulfitobacterium hafniense strain tce1. two fully identical copies of the insertion sequence isdha1, a new member of the is256 family, surround the gene cluster pceabct, a truncated gene for another transposase and a short open reading frame with homology to a member of the twin-arginine transport system (tata). evidence was obtained by so ... | 2005 | 15643941 |
| reductive dechlorination of beta-hexachlorocyclohexane (beta-hch) by a dehalobacter species in coculture with a sedimentibacter sp. | an anaerobic coculture was enriched from a hexachlorocyclohexane (hch) polluted soil. the coculture reductively dechlorinates the beta-hch isomer to benzene and chlorobenzene in a ratio of 0.5-2 depending on the amount of beta-hch degraded. the culture grows with h(2) as electron donor and beta-hch as electron acceptor, indicating that dechlorination is a respiratory process. phylogenetic analysis indicated that the coculture consists of two bacteria that are both related to gram-positive bacter ... | 2005 | 16329975 |
| growth of dehalobacter and dehalococcoides spp. during degradation of chlorinated ethanes. | mixed anaerobic microbial subcultures enriched from a multilayered aquifer at a former chlorinated solvent disposal facility in west louisiana were examined to determine the organism(s) involved in the dechlorination of the toxic compounds 1,2-dichloroethane (1,2-dca) and 1,1,2-trichloroethane (1,1,2-tca) to ethene. sequences phylogenetically related to dehalobacter and dehalococcoides, two genera of anaerobic bacteria that are known to respire with chlorinated ethenes, were detected through clo ... | 2006 | 16391074 |
| the effect of varying levels of sodium bicarbonate on polychlorinated biphenyl dechlorination in hudson river sediment cultures. | the addition of different concentrations of sodium bicarbonate had a profound effect on 2,3,4,5-chlorobiphenyl (2,3,4,5-cb) dechlorination in hudson river sediment cultures. the most extensive dechlorination was observed in cultures to which 100 mg l(-1) bicarbonate was added. cultures amended with 1000 mg l(-1) bicarbonate had the least extensive dechlorination, with 2,4-cb and 2,5-cb as predominant end-products. a significant loss of total chlorinated biphenyl mass was observed in cultures to ... | 2006 | 16817937 |
| a 1,1,1-trichloroethane-degrading anaerobic mixed microbial culture enhances biotransformation of mixtures of chlorinated ethenes and ethanes. | 1,1,1-trichloroethane (1,1,1-tca) is a common groundwater pollutant as a result of improper disposal and accidental spills. it is often found as a cocontaminant with trichloroethene (tce) and inhibits some tce-degrading microorganisms. 1,1,1-tca removal is therefore required for effective bioremediation of sites contaminated with mixed chlorinated organics. this study characterized ms, a 1,1,1-tca-degrading, anaerobic, mixed microbial culture derived from a 1,1,1-tca-contaminated site in the nor ... | 2006 | 17056695 |
| assessment of the natural attenuation of chlorinated ethenes in an anaerobic contaminated aquifer in the bitterfeld/wolfen area using stable isotope techniques, microcosm studies and molecular biomarkers. | the in situ degradation of chlorinated ethenes was assessed in an anaerobic aquifer using stable isotope fractionation approaches, microcosm studies and taxon specific detection of specific dehalogenating groups of bacteria. the aquifer in the bitterfeld/wolfen region in germany contained all chlorinated ethenes, benzene and toluene as contaminants. the concentrations and isotope composition of the chlorinated ethenes indicated biodegradation of the contaminants. microcosm studies confirmed the ... | 2007 | 17123579 |
| the dehalococcoides population in sediment-free mixed cultures metabolically dechlorinates the commercial polychlorinated biphenyl mixture aroclor 1260. | microbial reductive dechlorination of commercial polychlorinated biphenyl (pcb) mixtures (e.g., aroclors) in aquatic sediments is crucial to achieve detoxification. despite extensive efforts over nearly two decades, the microorganisms responsible for aroclor dechlorination remained elusive. here we demonstrate that anaerobic bacteria of the dehalococcoides group derived from sediment of the housatonic river (lenox, ma) simultaneously dechlorinate 64 pcb congeners carrying four to nine chlorines ... | 2007 | 17308182 |
| a novel reductive dehalogenase, identified in a contaminated groundwater enrichment culture and in desulfitobacterium dichloroeliminans strain dca1, is linked to dehalogenation of 1,2-dichloroethane. | a mixed culture dechlorinating 1,2-dichloroethane (1,2-dca) to ethene was enriched from groundwater that had been subjected to long-term contamination. in the metagenome of the enrichment, a 7-kb reductive dehalogenase (rd) gene cluster sequence was detected by inverse and direct pcr. the rd gene cluster had four open reading frames (orf) showing 99% nucleotide identity with pceb, pcec, pcet, and orf1 of dehalobacter restrictus strain dsmz 9455(t), a bacterium able to dechlorinate chlorinated et ... | 2007 | 17351102 |
| comparative analysis of three tetrachloroethene to ethene halorespiring consortia suggests functional redundancy. | three anaerobic, dechlorinating consortia were enriched from different sites using methanol and tetrachloroethene (pce) and maintained for approximately 3 years. these consortia were evaluated using chemical species analysis including distribution of dechlorination products, production of organic acids and methane, and using qualitative and quantitative pcr (qpcr), terminal restriction fragment length polymorphism (trflp), and denaturing gradient gel electrophoresis (dgge) with primers specific ... | 2007 | 17438773 |
| stable carbon isotope fractionation of chloroethenes by dehalorespiring isolates. | stable carbon isotope fractionation during the reductive dechlorination of chloroethenes by two bacterial strains that dechlorinate to ethene, dehalococcoides ethenogenes 195 and dehalococcoides sp. strain bav1 as well as sulfurospirillum multivorans and dehalobacter restrictus strain per-k23, isolates that do not dechlorinate past dce, are reported. fractionation by a dehalococcoides-containing enrichment culture is also measured for comparison to the isolates. all data adequately fit the rayle ... | 2007 | 17626425 |
| isolation and quantitative detection of tetrachloroethene (pce)-dechlorinating bacteria in unsaturated subsurface soils contaminated with chloroethenes. | the estimation of tetrachloethene (pce) dechlorinating-activity and identification of pce-dechlorinating bacteria were performed in 65 unsaturated subsurface soils (at a depth 30-60 cm) that were collected from 21 noncontaminated soils and 44 chloroethene-contaminated soils including four soils that dechlorinated pce to 1,2-cis-dichloroethene (cisdce) in situ. sixteen out of the 44 pce-contaminated soils and three out of the 21 noncontaminated soils dechlorinated pce to trichloroethene and cisdc ... | 2007 | 17884652 |
| structure analysis and performance of a microbial community from a contaminated aquifer involved in the complete reductive dechlorination of 1,1,2,2-tetrachloroethane to ethene. | an anaerobic microcosm set up with aquifer material from a 1,1,2,2-tetrachloroethane (teca) contaminated site and amended with butyrate showed a complete teca dechlorination to ethene. a structure analysis of the microbial community was performed by fluorescence in situ hybridization (fish) with already available and on purpose designed probes from sequences retrieved through 16s rdna clone library construction. fish was chosen as identification tool to evaluate in situ whether the retrieved seq ... | 2008 | 18431745 |
| pathways for the anaerobic microbial debromination of polybrominated diphenyl ethers. | the debromination pathways of seven polybrominated diphenyl ethers (pbdes) by three different cultures of anaerobic dehalogenating bacteria were investigated using comprehensive two-dimensional gas chromatography (gc x gc). the congeners analyzed were the five major components of the industrially used octa-bde mixture (octa-bdes 196, 203, and 197, hepta-bde 183, and hexa-bde 153) as well as the two most commonly detected pbdes in the environment, penta-bde 99 and tetra-bde 47. among the dehaloge ... | 2008 | 18497133 |
| molecular characterization of polychlorinated biphenyl-dechlorinating populations in contaminated sediments. | polychlorinated biphenyl (pcb)-dechlorinating microorganisms were characterized in pcb-contaminated sediments using amplified ribosomal dna restriction analysis (ardra). the sediments were prepared by spiking aroclor 1248 into pcb-free sediments, and were inoculated with microorganisms eluted from st. lawrence river sediments. pcb-free sediments inoculated with the same inoculum served as the control. four restriction fragment length polymorphism (rflp) groups in the eubacterial and two in the a ... | 2008 | 18545966 |
| a novel dehalobacter species is involved in extensive 4,5,6,7-tetrachlorophthalide dechlorination. | the purpose of this study was the enrichment and phylogenetic identification of bacteria that dechlorinate 4,5,6,7-tetrachlorophthalide (commercially designated "fthalide"), an effective fungicide for rice blast disease. sequential transfer culture of a paddy soil with lactate and fthalide produced a soil-free enrichment culture (designated the "kfl culture") that dechlorinated fthalide by using hydrogen, which is produced from lactate. phylogenetic analysis based on 16s rrna genes revealed the ... | 2009 | 19218402 |
| characterization of a dehalobacter coculture that dechlorinates 1,2-dichloroethane to ethene and identification of the putative reductive dehalogenase gene. | dehalobacter and "dehalococcoides" spp. were previously shown to be involved in the biotransformation of 1,1,2-trichloroethane (1,1,2-tca) and 1,2-dichloroethane (1,2-dca) to ethene in a mixed anaerobic enrichment culture. here we report the further enrichment and characterization of a dehalobacter sp. from this mixed culture in coculture with an acetobacterium sp. through a series of serial transfers and dilutions with acetate, h(2), and 1,2-dca, a stable coculture of acetobacterium and dehalob ... | 2009 | 19270140 |
| spatial and temporal distributions of geobacter lovleyi and dehalococcoides spp. during bioenhanced pce-napl dissolution. | the spatial and temporal distributions of multiple reductively dechlorinating bacteria were simultaneously assessed in a one-dimensional sand column containing a tetrachloroethene (pce) nonaqueous phase liquid (napl) source and associated plume zones. the column was uniformly inoculated with a pce-to-ethene dechlorinating microbial consortium that contained dehalococcoides spp., dehalobacter spp., and geobacter lovleyi strain sz. geobacter and dehalococcoides populations grew and colonized the c ... | 2009 | 19368201 |
| degradation of 1,2-dichloroethane by microbial communities from river sediment at various redox conditions. | insight into the pathways of biodegradation and external factors controlling their activity is essential in adequate environmental risk assessment of chlorinated aliphatic hydrocarbon pollution. this study focuses on biodegradation of 1,2-dichloroethane (1,2-dca) in microcosms containing sediment sourced from the european rivers ebro, elbe and danube. biodegradation was studied under different redox conditions. reductive dechlorination of 1,2-dca was observed with ebro and danube sediment with c ... | 2009 | 19501382 |
| microbial structure of an anaerobic bioreactor population that continuously dechlorinates 1,2-dichloropropane. | the bacterial diversity of an anaerobic 1,2-dichloropropane (dcp) dechlorinating bioreactor consortium derived from river sediment has been investigated by a combined molecular approach. by using rdna clone libraries, denaturing gradient gel electrophoresis and quantitative real-time pcr, both dehalococcoides ethenogenes- and dehalobacter restrictus-like 16s rdna sequences were found within the community. both species are known for reductive dechlorination of tetrachloroethene. furthermore, nume ... | 2002 | 19709202 |
| geochemistry and microbial diversity of a trichloroethene-contaminated superfund site undergoing intrinsic in situ reductive dechlorination. | this study explored the geochemistry and microbial diversity of a superfund site containing trichloroethene (tce) and an unusual co-pollutant, tetrakis(2-ethylbutoxy)silane. geochemical analysis of contaminated groundwater indicated subsurface anaerobiosis, reductive dechlorination of tce to predominantly cis-1,2-dichloroethene, and (transient) accumulation of 2-ethylbutanol and 2-ethylbutyrate as a result of tetrakis(2-ethylbutoxy)silane breakdown. comparative analysis of 106 16s rdna and 61 16 ... | 2002 | 19709219 |
| 1,1,1-trichloroethane and 1,1-dichloroethane reductive dechlorination kinetics and co-contaminant effects in a dehalobacter-containing mixed culture. | 1,1,1-trichloroethane (1,1,1-tca) is a common groundwater contaminant that can be reductively dechlorinated to 1,1-dichloroethane (1,1-dca) and monochloroethane, and can support the growth of certain dehalorespiring strains of dehalobacter we used reductive dehalogenase cell-free extract assays (with reduced methyl viologen) and whole cell suspension dechlorination assays (with hydrogen) and a dehalobacter-containing enrichment culture to explore the kinetics of l,1,1-tca and 1,1-dca reductive d ... | 2009 | 19764252 |
| spatial heterogeneity of dechlorinating bacteria and limiting factors for in situ trichloroethene dechlorination revealed by analyses of sediment cores from a polluted field site. | microbiological analyses of sediment samples were conducted to explore potentials and limitations for bioremediation of field sites polluted with chlorinated ethenes. intact sediment cores, collected by direct push probing from a 35-ha contaminated area, were analyzed in horizontal layers. cultivation-independent pcr revealed dehalococcoides to be the most abundant 16s rrna gene phylotype with a suspected potential for reductive dechlorination of the major contaminant trichloroethene (tce). in d ... | 2010 | 20041951 |
| chloroform respiration to dichloromethane by a dehalobacter population. | chloroform (cf), or trichloromethane, is an ubiquitous environmental pollutant because of its widespread industrial use, historically poor disposal and recalcitrance to biodegradation. chloroform is a potent inhibitor of metabolism and no known organism uses it as a growth substrate. we discovered that cf was rapidly and sustainably dechlorinated in the course of investigating anaerobic reductive dechlorination of 1,1,1-trichloroethane in a dehalobacter-containing culture. like 1,1,1-trichloroet ... | 2010 | 20089043 |
| characterization of microbial communities in the aqueous phase of a constructed model wetland treating 1,2-dichloroethene-contaminated groundwater. | the dynamics and composition of microbial communities in the aqueous phase of a model wetland supplied with cis- and trans-1,2-dichloroethenes (dce)-contaminated groundwater was characterized. pcr-denaturing gradient gel electrophoresis analysis of water samples obtained from different parts of the wetland revealed that changes of the bacterial community structure coincided with a succession of the hydrochemical conditions in the wetland, from oxic towards anoxic conditions. during this transiti ... | 2010 | 20100182 |
| reactive iron barriers: a niche enabling microbial dehalorespiration of 1,2-dichloroethane. | a reactive iron barrier in a contaminated aquifer with low ph was found to dechlorinate 1,2-dichloroethane (1,2-dca) in situ. this chlorinated ethane is known to resist abiotic reduction by zero valent iron. samples taken up-gradient and within the barrier were used to inoculate anaerobic batch cultures amended with various electron donors. cultures inoculated with groundwater from within the reactive iron barrier reduced 1,2-dca to ethene. the same effect could be achieved by simultaneously sup ... | 2010 | 20607230 |
| identification of molecular markers to follow up the bioremediation of sites contaminated with chlorinated compounds. | the use of microorganisms to clean up xenobiotics from polluted ecosystems (soil and water) represents an ecosustainable and powerful alternative to traditional remediation processes. recent developments in molecular-biology-based techniques have led to rapid and sensitive strategies for monitoring and identifying bacteria and catabolic genes involved in the degradation of xenobiotics. this chapter provides a description of recently developed molecular-biology-based techniques, such as pcr with ... | 2010 | 20830567 |
| insights into enzyme kinetics of chloroethane biodegradation using compound specific stable isotopes. | while compound specific isotope analysis (csia) has been used extensively to investigate remediation of chlorinated ethenes, to date considerably less information is available on its applicability to chlorinated ethanes. in this study, biodegradation of 1,1,1-trichloroethane (1,1,1-tca) and 1,1-dichloroethane (1,1-dca) was carried out by a dehalobacter-containing mixed culture. carbon isotope fractionation factors (ε) measured during whole cell degradation demonstrated that values for 1,1,1-tca ... | 2010 | 20831217 |
| characterization of microbial consortia that reductively dechlorinate 4-chlorophenol and transform phenol to benzoate enriched from estuarine sediment of lake shinji. | monochlorophenols were degraded to benzoate via phenol by the initial dechlorination and the subsequent conversion of phenol to benzoate in anaerobic sediment samples of estuarine lake shinji under methanogenic conditions. to characterize bacteria that dechlorinate 4-chlorophenol and transform phenol to benzoate, we analyzed the microbial community structure of the enrichment culture with each 4-chlorophenol and phenol by the limiting dilution method with polymerase chain reaction-denaturing gra ... | 2011 | 21328126 |
| natural and enhanced anaerobic degradation of 1,1,1-trichloroethane and its degradation products in the subsurface--a critical review. | 1,1,1-trichloroethane (tca) in groundwater is susceptible to a variety of natural degradation mechanisms. evidence of intrinsic decay of tca in aquifers is commonly observed; however, tca remains a persistent pollutant at many sites and some of the daughter products that accumulate from intrinsic decay of tca have been determined to be more toxic than the parent compound. research advances from the past decade indicate that in situ enhanced reductive dechlorination (erd) offers promise as a cost ... | 2011 | 21474158 |
| reductive dechlorination of polychlorinated biphenyls and dibenzo-p-dioxins in an enrichment culture containing dehalobacter species. | the dechlorination of polychlorinated biphenyls (pcbs) and polychlorinated dibenzo-p-dioxins was examined in an enrichment culture (kfl culture) that contained two phylotypes of dehalobacter, fth1 and fth2. the kfl culture dechlorinated 2,3,4,5-tetrachlorobiphenyl, 2,3,4-trichorobiphenyl (2,3,4-tricb), and 1,2,3-trichlorodibenzo-p-dioxin (1,2,3-tricdd). quantitative real-time pcr targeting fth1 and fth2 revealed significant increases with the addition of pcbs and 1,2,3-tricdd, suggesting halores ... | 2009 | 21566395 |
| a role for dehalobacter spp. in the reductive dehalogenation of dichlorobenzenes and monochlorobenzene. | previously, we demonstrated the reductive dehalogenation of dichlorobenzene (dcb) isomers to monochlorobenzene (mcb), and mcb to benzene in sediment microcosms derived from a chlorobenzene-contaminated site. in this study, enrichment cultures were established for each dcb isomer and each produced mcb and trace amounts of benzene as end products. mcb dehalogenation activity could only be transferred in sediment microcosms. the 1,2-dcb-dehalogenating culture was studied the most intensively. where ... | 2011 | 21732639 |
| dichloromethane fermentation by a dehalobacter sp. in an enrichment culture derived from pristine river sediment. | dichloromethane as the sole substrate supported growth of a dehalobacter sp. in an enrichment culture derived from non-contaminated river sediment. dcm was not reductively dechlorinated and acetate was produced, indicating dcm fermentation and further suggesting dehalobacter growth is not limited to organohalide respiration. | 2011 | 22179245 |
| use of γ-hexachlorocyclohexane as a terminal electron acceptor by an anaerobic enrichment culture. | the use of γ-hexachlorocyclohexane (hch) as a terminal electron acceptor via organohalide respiration was demonstrated for the first time with an enrichment culture grown in a sulfate-free hepes-buffered anaerobic mineral salts medium. the enrichment culture was initially developed with soil and groundwater from an industrial site contaminated with hch isomers, chlorinated benzenes, and chlorinated ethenes. when hydrogen served as the electron donor, 79-90% of the electron equivalents from hydro ... | 2011 | 21983168 |
| Complete chloroform dechlorination by organochlorine respiration and fermentation. | Chloroform (CF, CHCl(3) ) is a recalcitrant and toxic environmental pollutant. In this communication we report for the first time a microbial community capable of complete CF dechlorination by metabolic processes. Cultures derived from subsurface soil (3.5 m) could sustain complete dechlorination of CF at levels of least 360 µM at a rate of 40 µM per day. Scrutiny of CF dechlorination revealed two metabolic processes at work. First, CF was respired to dichloromethane (DCM, CH(2) Cl(2) ), which w ... | 2011 | 22118646 |