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1.
The study investigates two functional genes for toluene degradation across three redox conditions (nitrate and sulfate amended and methanogenic). The genes targeted include benzylsuccinate synthase α-subunit (bssA) and a gene recently identified as being a strong indicator of anaerobic aromatic degradation, called 6-oxocylcohex-1-ene-1-carbonyl-CoA hydrolase (bamA). In all, sixteen different anaerobic toluene degrading microcosms were investigated using several primers sets targeting bssA and one primer set targeting bamA. One bssA primer set (7772f/8546r) was the most successful in producing a strong amplicon (eight from sixteen) with the other bssA primers sets producing strong amplicons in six or less samples. In contrast, the bamA primer set (bam-sp9 and bam-asp1) produced a strong amplicon in DNA extracted from all except one microcosm. Partial bssA and bamA sequences were obtained for a number of samples and compared to those available in GenBank. The partial bssA sequences (from nitrate amended and methanogenic microcosms) were most similar to Thauera sp. DNT-1, Thauera aromatica, Aromatoleum aromaticum EbN1 and bssA clones from a study involving sulfate reducing toluene degradation. The bamA sequences obtained could be placed into five previously defined clades (bamA-clade 1, Georgfuchsia/Azoarcus, Magnetospirillum/Thauera Syntrophus and Geobacter clades), with the placement generally depending on redox conditions. Gene numbers were also correlated with toluene degradation and the final gene number for both genes differed considerably between the range of redox conditions. The work is the first in depth investigation of bamA diversity over a range of redox conditions and inoculum sources. 相似文献
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Anke Kuppardt Sabine Kleinsteuber Carsten Vogt Tillmann Lüders Hauke Harms Antonis Chatzinotas 《Microbial ecology》2014,68(2):222-234
Three toluene-degrading microbial consortia were enriched under sulphate-reducing conditions from different zones of a benzene, toluene, ethylbenzene and xylenes (BTEX) plume of two connected contaminated aquifers. Two cultures were obtained from a weakly contaminated zone of the lower aquifer, while one culture originated from the highly contaminated upper aquifer. We hypothesised that the different habitat characteristics are reflected by distinct degrader populations. Degradation of toluene with concomitant production of sulphide was demonstrated in laboratory microcosms and the enrichment cultures were phylogenetically characterised. The benzylsuccinate synthase alpha-subunit (bssA) marker gene, encoding the enzyme initiating anaerobic toluene degradation, was targeted to characterise the catabolic diversity within the enrichment cultures. It was shown that the hydrogeochemical parameters in the different zones of the plume determined the microbial composition of the enrichment cultures. Both enrichment cultures from the weakly contaminated zone were of a very similar composition, dominated by Deltaproteobacteria with the Desulfobulbaceae (a Desulfopila-related phylotype) as key players. Two different bssA sequence types were found, which were both affiliated to genes from sulphate-reducing Deltaproteobacteria. In contrast, the enrichment culture from the highly contaminated zone was dominated by Clostridia with a Desulfosporosinus-related phylotype as presumed key player. A distinct bssA sequence type with high similarity to other recently detected sequences from clostridial toluene degraders was dominant in this culture. This work contributes to our understanding of the niche partitioning between degrader populations in distinct compartments of BTEX-contaminated aquifers. 相似文献
3.
The assessment of biodegradation activity in contaminated aquifers is critical to demonstrate the performance of bioremediation
and natural attenuation and to parameterize models of contaminant plume dynamics. Real time quantitative PCR (qPCR) was used
to target the catabolic bssA gene (coding for benzylsuccinate synthase) and a 16S rDNA phylogenetic gene (for total Bacteria) as potential biomarkers to infer on anaerobic toluene degradation rates. A significant correlation (P = 0.0003) was found over a wide range of initial toluene concentrations (1–100 mg/l) between toluene degradation rates and
bssA concentrations in anaerobic microcosms prepared with aquifer material from a hydrocarbon contaminated site. In contrast,
the correlation between toluene degradation activity and total Bacteria concentrations was not significant (P = 0.1125). This suggests that qPCR targeting of functional genes might offer a simple approach to estimate in situ biodegradation
activity, which would enhance site investigation and modeling of natural attenuation at hydrocarbon-contaminated sites. 相似文献
4.
Depth-Resolved Quantification of Anaerobic Toluene Degraders and Aquifer Microbial Community Patterns in Distinct Redox Zones of a Tar Oil Contaminant Plume 总被引:3,自引:0,他引:3 下载免费PDF全文
Christian Winderl Bettina Anneser Christian Griebler Rainer U. Meckenstock Tillmann Lueders 《Applied microbiology》2008,74(3):792-801
Microbial degradation is the only sustainable component of natural attenuation in contaminated groundwater environments, yet its controls, especially in anaerobic aquifers, are still poorly understood. Hence, putative spatial correlations between specific populations of key microbial players and the occurrence of respective degradation processes remain to be unraveled. We therefore characterized microbial community distribution across a high-resolution depth profile of a tar oil-impacted aquifer where benzene, toluene, ethylbenzene, and xylene (BTEX) degradation depends mainly on sulfate reduction. We conducted depth-resolved terminal restriction fragment length polymorphism fingerprinting and quantitative PCR of bacterial 16S rRNA and benzylsuccinate synthase genes (bssA) to quantify the distribution of total microbiota and specific anaerobic toluene degraders. We show that a highly specialized degrader community of microbes related to known deltaproteobacterial iron and sulfate reducers (Geobacter and Desulfocapsa spp.), as well as clostridial fermenters (Sedimentibacter spp.), resides within the biogeochemical gradient zone underneath the highly contaminated plume core. This zone, where BTEX compounds and sulfate—an important electron acceptor—meet, also harbors a surprisingly high abundance of the yet-unidentified anaerobic toluene degraders carrying the previously detected F1-cluster bssA genes (C. Winderl, S. Schaefer, and T. Lueders, Environ. Microbiol. 9:1035-1046, 2007). Our data suggest that this biogeochemical gradient zone is a hot spot of anaerobic toluene degradation. These findings show that the distribution of specific aquifer microbiota and degradation processes in contaminated aquifers are tightly coupled, which may be of value for the assessment and prediction of natural attenuation based on intrinsic aquifer microbiota. 相似文献
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Enhanced Anaerobic Biodegradation of Benzene-Toluene-Ethylbenzene-Xylene-Ethanol Mixtures in Bioaugmented Aquifer Columns 总被引:2,自引:0,他引:2 下载免费PDF全文
Methanogenic flowthrough aquifer columns were used to investigate the potential of bioaugmentation to enhance anaerobic benzene-toluene-ethylbenzene-xylene (BTEX) degradation in groundwater contaminated with ethanol-blended gasoline. Two different methanogenic consortia (enriched with benzene or toluene and o-xylene) were used as inocula. Toluene was the only hydrocarbon degraded within 3 years in columns that were not bioaugmented, although anaerobic toluene degradation was observed after only 2 years of acclimation. Significant benzene biodegradation (up to 88%) was observed only in a column bioaugmented with the benzene-enriched methanogenic consortium, and this removal efficiency was sustained for 1 year with no significant decrease in permeability due to bioaugmentation. Benzene removal was hindered by the presence of toluene, which is a more labile substrate under anaerobic conditions. Real-time quantitative PCR analysis showed that the highest numbers of bssA gene copies (coding for benzylsuccinate synthase) occurred in aquifer samples exhibiting the highest rate of toluene degradation, which suggests that this gene could be a useful biomarker for environmental forensic analysis of anaerobic toluene bioremediation potential. bssA continued to be detected in the columns 1 year after column feeding ceased, indicating the robustness of the added catabolic potential. Overall, these results suggest that anaerobic bioaugmentation might enhance the natural attenuation of BTEX in groundwater contaminated with ethanol-blended gasoline, although field trials would be needed to demonstrate its feasibility. This approach may be especially attractive for removing benzene, which is the most toxic and commonly the most persistent BTEX compound under anaerobic conditions. 相似文献
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Molecular diversity and distribution of aromatic hydrocarbon-degrading anaerobes across a landfill leachate plume 总被引:1,自引:0,他引:1
Natural attenuation of the mono‐aromates benzene, toluene, ethylbenzene and xylene occurs under iron‐reducing conditions in a leachate‐contaminated aquifer near the Banisveld landfill, the Netherlands. The diversity of mono‐aromate‐degrading microorganisms was studied by targeting functional genes encoding benzylsuccinate synthase α‐subunit (bssA) and 6‐oxocyclohex‐1‐ene‐1‐carbonyl‐CoA hydrolase (bamA). Sixty‐four bssA and 188 bamA variants were sequenced from groundwater sampled along the pollution plume in 1999 and 2004. Species containing bssA sequences closest affiliated (> 91%) with the betaprotebacterium Georgfuchsia toluolica were the dominant alkylbenzene degraders (89% of bssA sequences). bssA genes were found at more than 10‐fold lower copy numbers than bamA genes, of which only a small fraction (< 2%) was closely related to the genes of Georgfuchsia. bamA gene diversity was high and bamA‐based community composition was primarily affected by dissolved organic carbon (DOC) and ferrous iron concentrations. bamA sequences closest related to Geobacteraceae were dominantly (43.2%) observed and the presence of Geobacteraceae‐related bamA sequences was associated with DOC. Our results indicate a key role for specialized Georgfuchsia spp. in the degradation of alkylbenzenes, whereas Geobacteraceae are involved in degradation of aromatics other than toluene and xylene. 相似文献
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Milán Farkas Sándor Szoboszlay Tibor Benedek Fruzsina Révész Péter Gábor Veres Balázs Kriszt András Táncsics 《Folia microbiologica》2017,62(1):63-71
Dissimilatory iron-reducing bacteria are commonly found in microbial communities of aromatic hydrocarbon-contaminated subsurface environments where they often play key role in the degradation of the contaminants. The Siklós benzene, toluene, ethylbenzene, and xylene (BTEX)-contaminated area is one of the best characterized petroleum hydrocarbon-contaminated sites of Hungary. Continuous monitoring of the microbial community in the center of the contaminant plume indicated the presence of an emerging Geobacter population and a Rhodoferax phylotype highly associated with aromatic hydrocarbon-contaminated subsurface environments. The aim of the present study was to make an initial effort to enrich Rhodoferax-related and other dissimilatory iron-reducing bacteria from this environment. Accordingly, four slightly different freshwater media were used to enrich Fe(III) reducers, differing only in the form of nitrogen source (organic, inorganic nitrogen or gaseous headspace nitrogen). Although enrichment of the desired Rhodoferax phylotype was not succeeded, Geobacter-related bacteria were readily enriched. Moreover, the different nitrogen sources caused the enrichment of different Geobacter species. Investigation of the diversity of benzylsuccinate synthase gene both in the enrichments and in the initial groundwater sample indicated that the Geobacter population in the center of the contaminant plume may not play a significant role in the anaerobic degradation of toluene. 相似文献
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Alejandro Acosta-González Ramon Rosselló-Móra Silvia Marqués 《Applied and environmental microbiology》2013,79(12):3667-3676
The potential of hydrocarbon biodegradation in marine sediments was determined through the detection of a functional biomarker, the bssA gene, coding for benzylsuccinate synthase, the key enzyme of anaerobic toluene degradation. Eight bssA clone libraries (409 sequences) were constructed from polluted sediments affected by the Prestige oil spill in the Atlantic Islands National Park and from hydrocarbon-amended sediment microcosms in Mallorca. The amplified products and database-derived bssA-like sequences grouped into four major clusters, as determined by phylogenetic reconstruction, principal coordinate analysis (PCoA), and a subfamily prediction tool. In addition to the classical bssA sequences that were targeted, we were able to detect sequences homologous to the naphthylmethylsuccinate synthase gene (nmsA) and the alkylsuccinate synthase gene (assA), the bssA homologues for anaerobic 2-methylnaphthalene and alkane degradation, respectively. The detection of bssA-like variants was determined by the persistence and level of pollution in the marine samples. The observed level of gene diversity was lower in the Mallorca sediments, which were dominated by assA-like sequences. In contrast, the Atlantic Islands samples, which were highly contaminated with methylnaphthalene-rich crude oil, showed a high proportion of nmsA-like sequences. Some of the detected genes were phylogenetically related to Deltaproteobacteria communities, previously described as the predominant hydrocarbon degraders at these sites. Differences between all detected bssA-like genes described to date indicate separation between marine and terrestrial sequences and further subgrouping according to taxonomic affiliation. Global analysis suggested that bssA homologues appeared to cluster according to substrate specificity. We observed undetected divergent gene lineages of bssA homologues, which evidence the existence of new degrader groups in these environments. 相似文献
9.
Denitrification was assayed by the acetylene blockage technique in slurried core material obtained from a freshwater sand and gravel aquifer. The aquifer, which has been contaminated with treated sewage for more than 50 years, had a contaminant plume greater than 3.5-km long. Near the contaminant source, groundwater nitrate concentrations were greater than 1 mM, whereas 0.25 km downgradient the central portion of the contaminant plume was anoxic and contained no detectable nitrate. Samples were obtained along the longitudinal axis of the plume (0 to 0.25 km) at several depths from four sites. Denitrification was evident at in situ nitrate concentrations at all sites tested; rates ranged from 2.3 to 260 pmol of N2O produced (g of wet sediment)−1 h−1. Rates were highest nearest the contaminant source and decreased with increasing distance downgradient. Denitrification was the predominant nitrate-reducing activity; no evidence was found for nitrate reduction to ammonium at any site. Denitrifying activity was carbon limited and not nitrate limited, except when the ambient nitrate level was less than the detection limit, in which case, even when amended with high concentrations of glucose and nitrate, the capacity to denitrify on a short-term basis was lacking. These results demonstrate that denitrification can occur in groundwater systems and, thereby, serve as a mechanism for nitrate removal from groundwater. 相似文献
10.
To understand the potential for toluene removal under electron acceptor depleted conditions, stable isotope probing (SIP) was applied to a methanogenic toluene degrading culture to identify the microorganisms responsible for toluene assimilation. Both bacterial and archaeal communities were investigated. The approach involved addition of labeled and unlabeled toluene to microcosms, DNA extraction, ultracentrifugation, and analysis of the generated fractions, as well as the total genomic DNA. Three genes were investigated in the fractions, including the 16S rRNA gene, bssA (encoding for benzylsuccinate synthase α-subunit) and bamA (encoding for 6-oxocylcohex-1-ene-1-carbonyl-CoA hydrolase). Analysis of the total genomic 16S rRNA gene clone library indicated the microbial community was reasonably diverse, containing microorganisms from six phyla (Proteobacteria, Firmicutes, Acidobacteria, Actinobacteria, Deferribacteres, Bacteroidetes). In contrast, only four phylotypes were found in the heavy fraction 16S rRNA gene clone library (from three phyla: Firmicutes, Acidobacteria, Actinobacteria). When these data were correlated with the TRFLP fragments enriched in the heavy fractions, three phylotypes were identified. Specifically, a Desulfosporosinus phylotype was highly enriched in the heavy fractions and was therefore the key consumer of the labeled carbon from toluene. Two other phylotypes, Peptostreptococcaceae and Pseudonocardia were presumed to consume daughter products and produce methane precursors, which in turn were likely utilized by Methanomicrobia to produce methane. Further, the SIP results suggested that the enzymes encoding by functional genes (bssA and bamA) were likely to be harbored by the Desulfosporosinus phylotype. 相似文献
11.
Agnieszka Herzyk Piotr Maloszewski Shiran Qiu Martin Elsner Christian Griebler 《Biodegradation》2014,25(3):325-336
Pristine and energy-limited aquifers are considered to have a low resistance and resilience towards organic pollution. An experiment in an indoor aquifer system revealed an unexpected high intrinsic potential for the attenuation of a short-term toluene contamination. A 30 h pulse of 486 mg of toluene, used as a model contaminant, and deuterated water (D2O) through an initially pristine, oxic, and organic carbon poor sandy aquifer revealed an immediate aerobic toluene degradation potential. Based on contaminant and tracer break-through curves, as well as mass balance analyses and reactive transport modelling, a contaminant removal of 40 % over a transport distance of only 4.2 m in less than one week of travel time was obtained. The mean first-order degradation rate constant was λ = 0.178 day?1, corresponding to a half-life time constant T1/2 of 3.87 days. Toluene-specific stable carbon isotope analysis independently proved that the contaminant mass removal can be attributed to microbial biodegradation. Since average doubling times of indigenous bacterial communities were in the range of months to years, the aerobic biodegradation potential observed is assumed to be present and active in the pristine, energy-limited groundwater ecosystems at any time. Follow-up experiments and field studies will help to quantify the immediate natural attenuation potential of aquifers for selected priority contaminants and will try to identify the key-degraders within the autochthonous microbial communities. 相似文献
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Pesticide Side Effects in an Agricultural Soil Ecosystem as Measured by amoA Expression Quantification and Bacterial Diversity Changes 总被引:1,自引:0,他引:1
Louise Feld Mathis Hjort Hjelms? Morten Schostag Nielsen Anne Dorthe Jacobsen Regin R?nn Flemming Ekelund Paul Henning Krogh Bjarne Westergaard Strobel Carsten Suhr Jacobsen 《PloS one》2015,10(5)
16.
R A Williams K A Shuttle J L Kunkler E L Madsen S W Hooper 《Journal of industrial microbiology & biotechnology》1997,18(2-3):177-188
An industrial site contaminated with a mixture of volatile organic compounds in its subsurface differed from previously reported
locations in that the contamination consisted of a mixture of chlorinated, brominated, and non-halogenated aromatic and aliphatic
solvents in an alluvial aquifer. The source area was adjacent to a river. Of the contaminants present in the aquifer, benzene,
toluene, and chlorobenzene (BTC) were of primary concern. Studies of the physical, chemical, and microbiological characteristics
of site groundwater were conducted. The studies concentrated on BTC, but also addressed the fate of the other aquifer VOCs.
Gas chromatographic analyses performed on laboratory microcosms demonstrated that subsurface microorganisms were capable
of BTC degradation. Mineralization of BTC was demonstrated by the release of 14CO2 from radiolabelled BTC. In the field, distribution patterns of nutrients and electron acceptors were consistent with expression
of in situ microbial metabolic activity: methane, conductivity, salinity and o-phosphate concentrations were all positively correlated with contaminant concentration; while oxidation-reduction potential,
nitrate, dissolved oxygen and sulfate concentrations were negatively correlated. Total aerobes, aerotolerant anaerobes, BTC-specific
degraders, and acridine orange direct microscopic microorganism counts were strongly and positively correlated with field
contaminant concentrations. The relative concentrations of benzene and toluene were lower away from the core of the plume
compared to the less readily metabolized compound, chlorobenzene. Hydrodynamic modeling of electron-acceptor depletion conservatively
estimated that 450 kg of contaminant have been removed from the subsurface yearly. Models lacking a biodegradation term
predicted that 360 kg of contaminant would reach the river annually, which would result in measurable contaminant concentrations.
River surveillance, however, has only rarely detected these compounds in the sediment and then only at trace concentrations.
Thus, the combination of field modeling, laboratory studies, and site surveillance data confirm that significant in situ biodegradation of the contaminants has occurred. These studies establish the presence of intrinsic bioremediation of groundwater
contaminants in this unusual industrial site subsurface habitat.
Received 01 December 1995/ Accepted in revised form 27 July 1996 相似文献
17.
Jehmlich N Kleinsteuber S Vogt C Benndorf D Harms H Schmidt F Von Bergen M Seifert J 《Journal of applied microbiology》2010,109(6):1937-1945
Aims: This study intended to unravel the physiological interplay in an anaerobic microbial community that degrades toluene under sulfate‐reducing conditions combining proteomic and genetic techniques. Methods and Results: An enriched toluene‐degrading community (Zz5‐7) growing in batch cultures was investigated by DNA‐ and protein‐based analyses. The affiliation and diversity of the community were analysed using 16S ribosomal RNA (rRNA) genes as a phylogenetic marker as well as bssA and dsrAB genes as functional markers. Metaproteome analysis was carried out by a global protein extraction and a subsequent protein separation by two‐dimensional gel electrophoresis (2‐DE). About 85% of the proteins in the spots were identified by nano‐liquid chromatography coupled with electrospray mass spectrometry (nano‐LC–ESI‐MS/MS) analysis. DNA sequencing of bssA and the most abundant dsrAB amplicons revealed high similarities to a member of the Desulfobulbaceae, which was also predominant according to 16S rRNA gene amplicons. Metaproteome analysis provided 202 unambiguous protein identifications derived from 236 unique protein spots. The proteins involved in anaerobic toluene activation, dissimilatory sulfate reduction, hydrogen production/consumption and autotrophic carbon fixation were mainly affiliated to members of the Desulfobulbaceae and several other Deltaproteobacteria. Conclusion: Phylogenetic and metaproteomic analyses revealed a member of the Desulfobulbaceae as the key player of anaerobic toluene degradation in a sulfate‐reducing consortium. Significance and Impact of the Study: This is the first study that combines genetic and proteomic analyses to indicate the interactions in an anaerobic toluene‐degrading microbial consortium. 相似文献
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Olivia U Mason Terry C Hazen Sharon Borglin Patrick S G Chain Eric A Dubinsky Julian L Fortney James Han Hoi-Ying N Holman Jenni Hultman Regina Lamendella Rachel Mackelprang Stephanie Malfatti Lauren M Tom Susannah G Tringe Tanja Woyke Jizhong Zhou Edward M Rubin Janet K Jansson 《The ISME journal》2012,6(9):1715-1727
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Matt A. Limmer Jordan Wilson David Westenberg Amy Lee Mark Siegman Joel G. Burken 《International journal of phytoremediation》2018,20(7):666-674
Phytoremediation is a sustainable remedial approach, although performance efficacy is rarely reported. In this study, we assessed a phytoremediation plot treating benzene, toluene, and chlorobenzene. A comparison of the calculated phytoremediation removal rate with estimates of onsite contaminant mass was used to forecast cleanup periods. The investigation demonstrated that substantial microbial degradation was occurring in the subsurface. Estimates of transpiration indicated that the trees planted were removing approximately 240,000 L of water per year. This large quantity of water removal implies substantial removal of contaminant due to large amounts of contaminants in the groundwater; however, these contaminants extensively sorb to the soil, resulting in large quantities of contaminant mass in the subsurface. The total estimate of subsurface contaminant mass was also complicated by the presence of non-aqueous phase liquids (NAPL), additional contaminant masses that were difficult to quantify. These uncertainties of initial contaminant mass at the site result in large uncertainty in the cleanup period, although mean estimates are on the order of decades. Collectively, the model indicates contaminant removal rates on the order of 10?2–100 kg/tree/year. The benefit of the phytoremediation system is relatively sustainable cleanup over the long periods necessary due to the presence of NAPL. 相似文献