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1.
World J Microbiol Biotechnol ; 36(2): 29, 2020 Feb 03.
Artigo em Inglês | MEDLINE | ID: mdl-32016527

RESUMO

Short-chain halogenated aliphatic hydrocarbons (e.g. perchloroethene, trichloroethene) are among the most toxic environmental pollutants. Perchloroethene and trichloroethene can be dechlorinated to non-toxic ethene through reductive dechlorination by Dehalococcoides sp. Bioaugmentation, applying cultures containing organohalide-respiring microorganisms, is a possible technique to remediate sites contaminated with chlorinated ethenes. Application of site specific inocula is an efficient alternative solution. Our aim was to develop site specific dechlorinating microbial inocula by enriching microbial consortia from groundwater contaminated with trichloroethene using microcosm experiments containing clay mineral as solid phase. Our main goal was to develop fast and reliable method to produce large amount (100 L) of bioactive agent with anaerobic fermentation technology. Polyphasic approach has been applied to monitor the effectiveness of dechlorination during the transfer process from bench-scale (500 mL) to industrial-scale (100 L). Gas chromatography measurement and T-RFLP (Terminal Restriction Fragment Length Polymorphism) revealed that the serial subculture of the enrichments shortened the time-course of the complete dechlorination of trichloroethene to ethene and altered the composition of bacterial communities. Complete dechlorination was observed in enrichments with significant abundance of Dehalococcoides sp. cultivated at 8 °C. Consortia incubated in fermenters at 18 °C accelerated the conversion of TCE to ethene by 7-14 days. Members of the enrichments belong to the phyla Bacteroidetes, Chloroflexi, Proteobacteria and Firmicutes. According to the operational taxonomic units, main differences between the composition of the enrichment incubated at 8 °C and 18 °C occurred with relative abundance of acetogenic and fermentative species. In addition to the temperature, the site-specific origin of the microbial communities and the solid phase applied during the fermentation technique contributed to the development of a unique microbial composition.


Assuntos
Anaerobiose/fisiologia , Bactérias/metabolismo , Biodegradação Ambiental , Argila/química , Microbiota/fisiologia , Bactérias/classificação , Bactérias/genética , Bactérias/isolamento & purificação , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Bacteroidetes/genética , Bacteroidetes/metabolismo , Chloroflexi/genética , Chloroflexi/metabolismo , DNA Bacteriano/genética , DNA Bacteriano/isolamento & purificação , Fermentação , Firmicutes/genética , Firmicutes/metabolismo , Geobacter/genética , Geobacter/metabolismo , Água Subterrânea/microbiologia , Consórcios Microbianos , Polimorfismo de Fragmento de Restrição , Proteobactérias/genética , Proteobactérias/metabolismo , RNA Ribossômico 16S/genética , RNA Ribossômico 16S/isolamento & purificação , Tricloroetileno/química , Microbiologia da Água , Poluentes Químicos da Água/metabolismo
2.
Chemosphere ; 238: 124596, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31524629

RESUMO

Deteriorated environmental conditions during the bioremediation of trichloroethene (TCE)-polluted groundwater cause decreased treatment efficiencies. This study assessed the effect of applying immobilized Clostridium butyricum (a hydrogen-producing bacterium) in silica gel on enhancing the reductive dechlorination efficiency of TCE with the slow polycolloid-releasing substrate (SPRS) supplement in groundwater. The responses of microbial communities with the immobilized system (immobilized Clostridium butyricum and SPRS amendments) were also characterized by the metagenomics assay. A complete TCE removal in microcosms was obtained within 30 days with the application of this immobilized system via reductive dechlorination processes. An increase in the population of Dehalococcoides spp. was observed using the quantitative polymerase chain reaction (qPCR) analysis. Results of metagenomics assay reveal that the microbial communities in the immobilized system were distinct from those in systems with SPRS only. Bacterial communities associated with TCE biodegradation also increased in microcosms treated with the immobilized system. The immobilized system shows a great potential to promote the TCE dechlorination efficiency, and the metagenomics-based approach provides detailed insights into dechlorinating microbial community dynamics. The results would be helpful in designing an in situ immobilized system to enhance the bioremediation efficiency of TCE-contaminated groundwater.


Assuntos
Chloroflexi/metabolismo , Clostridium butyricum/metabolismo , Água Subterrânea/química , Tricloroetileno/metabolismo , Biodegradação Ambiental , Chloroflexi/crescimento & desenvolvimento , Halogenação , Metagenômica , Microbiota/fisiologia , Sílica Gel
3.
Environ Int ; 133(Pt B): 105245, 2019 12.
Artigo em Inglês | MEDLINE | ID: mdl-31683156

RESUMO

Dehalococcoides is able to completely dehalogenate tetrachloroethene (PCE) and trichloroethene (TCE) to ethene (ETH). However, the dechlorination efficiency of Dehalococcoides is low and result in the accumulation of toxic intermediates. In this study, Shewanella oneidensis MR-1 (S. oneidensis MR-1) was added to the Dehalococcoides-containing culture and the complete TCE to ETH dechlorination was shortened from 24 days to 16 days. Dehalococcoides-targeted 16S rRNA gene and two model reductive dehalogenase (RDase) genes (tceA and vcrA), responsible for dechlorinating TCE to vinyl chloride (VC) and VC to ETH respectively, were characterized. Results showed that S. oneidensis MR-1 has no effect on the cell growth while the RDase genes expression was up-regulated and the RDase activity of Dehalococcoides was elevated. The mRNA abundance of vcrA increased approximately tenfold along with the increased concentration of vitamin B12 (cyanocobalamin). Interestingly, the addition of S. oneidensis MR-1 increased the concentration of vitamin B12 by affecting the microbial community structure. Therefore, the addition of S. oneidensis MR-1 might have a positive effect on regulating the activity of RDase of functional microorganisms and uptake of vitamin B12, and further provided a practical vision of chloroethene dechlorination by the Dehalococcoides-containing culture.


Assuntos
Cloro/metabolismo , Chloroflexi/metabolismo , Microbiota , Shewanella/metabolismo , Tricloroetileno/metabolismo , Biodegradação Ambiental , Halogenação
4.
Environ Sci Pollut Res Int ; 26(33): 34459-34467, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31642015

RESUMO

The anaerobic biodegradation of 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) was investigated using enrichment cultures from freshwater sediments at two different sites in the region of Halle, central Germany. 2,4,5-T and different organic acids or hydrogen were added as possible electron acceptor and electron donors, respectively. The primary enrichment cultures from Saale river sediment completely degraded 2,4,5-T to 3-chlorophenol (3-CP) (major product) and 3,4-dichlorophenol (3,4-DCP) during a 28-day incubation period. Subcultures showed ether cleavage of 2,4,5-T to 2,4,5-trichlorophenol and its stoichiometric dechlorination to 3-CP only in the presence of butyrate. In contrast, the primary enrichment culture from sediment of Posthorn pond dechlorinated 2,4,5-T to 2,5-dichlorophenoxyacetic acid (2,5-D), which, in the presence of butyrate, was degraded further to products such as 3,4-DCP, 2,5-DCP, and 3CP, indicating ether cleaving activities and subsequent dechlorination steps. Experiments with pure cultures of Dehalococcoides mccartyi and Desulfitobacterium hafniense demonstrated their specific dechlorination steps within the overall 2,4,5-T degradation pathways. The results indicate that the route and efficiency of anaerobic 2,4,5-T degradation in the environment depend heavily on the microorganisms present and the availability of slowly fermentable organic compounds.


Assuntos
Ácido 2,4,5-Triclorofenoxiacético/metabolismo , Biodegradação Ambiental , Poluentes Químicos da Água/metabolismo , Anaerobiose , Chloroflexi/metabolismo , Clorofenóis , Desulfitobacterium , Água Doce , Alemanha , Halogenação , Herbicidas , Fenóis/metabolismo , Rios
5.
Chemosphere ; 237: 124460, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31374391

RESUMO

ISCO using activated sodium persulphate is a widely used technology for treating chlorinated solvent source zones. In sensitive areas, however, high groundwater sulphate concentrations following treatment may be a drawback. In situ biogeochemical transformation, a technology that degrades contaminants via reduced iron minerals formed by microbial activity, offers a potential solution for such sites, the bioreduction of sulphate and production of iron sulphides that abiotically degrade chlorinated ethenes acting as a secondary technology following ISCO. This study assesses this approach in the field using hydrochemical and molecular tools, solid phase analysis and geochemical modelling. Following a neutralisation and bioaugmentation, favourable conditions for iron- and sulphate-reducers were created, resulting in a remarkable increase in their relative abundance. The abundance of dechlorinating bacteria (Dehalococcoides mccartyi, Dehalobacter sp. and Desulfitobacterium spp.) remained low throughout this process. The activity of iron- and sulphate-reducers was further stimulated through application of magnetite plus starch and microiron plus starch, resulting in an increase in ferrous iron concentration (from

Assuntos
Recuperação e Remediação Ambiental/métodos , Água Subterrânea/química , Poluentes Químicos da Água/metabolismo , Purificação da Água/métodos , Cloro/metabolismo , Chloroflexi/metabolismo , República Tcheca , Desulfitobacterium/metabolismo , Etilenos/metabolismo , Água Subterrânea/análise , Água Subterrânea/microbiologia , Halogenação , Ferro/metabolismo , Oxirredução , Peptococcaceae/metabolismo , Compostos de Sódio , Solventes/metabolismo , Sulfatos/metabolismo , Tetracloroetileno/análise , Tetracloroetileno/metabolismo , Tricloroetileno/análise , Tricloroetileno/metabolismo , Poluentes Químicos da Água/análise
6.
Chemosphere ; 233: 697-704, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31195274

RESUMO

Trichloroethylene (TCE) is one of the most ubiquitous halogenated organic compounds of concerns of carcinogens in groundwater in Taiwan. Bioremediation has been recognized as a cost-effective approach in reducing TCE concentration. Five pilot-scale wells were constructed to monitor TCE concentrations in contaminated groundwater. With injection of EOS®, TCE was effectively degraded to 42%-93% by the end of 175 days. The biostimulation with EOS® was useful in establishing a micro-site anaerobic but with limited contribution. Dilution of the aquifer movement also caused the TCE reduction among injection and monitoring wells. The degradability was affected by the location and the proximity from the injection well. TCE concentrations found to be negatively correlated with the associated Dehalococcoides spp. and functional genes levels. Dhc concentration of 108 copies L-1 caused the initial 40% of TCE degradation. The well with the optimal degradation owned tceA of 109 cells L-1. T-RFLP results indicate the wells with the superior TCE degradability also performed the highest Shannon index number (means the highest diversity), which occurred on the same day that Dhc levels started to enlarge. Desulfovibrio desulfuricans and Desulfuromonas chloroethenica were predominant species identified in the T-RFLP fingerprint profile. In brief, a variety of different factors including well locations, geochemical indicators, and microbial contribution were useful to explain the site-specific optimal TCE remediation approach. The consistence among TCE degradation, Dhc growing pattern, functional gene levels, and the dynamics of the microbial community structure present the novelty of this study.


Assuntos
Recuperação e Remediação Ambiental/métodos , Tricloroetileno/metabolismo , Poluentes Químicos da Água/metabolismo , Biodegradação Ambiental , Chloroflexi/metabolismo , Água Subterrânea/química , Halogenação , Microbiota , Taiwan , Tricloroetileno/análise , Tricloroetileno/química , Poluentes Químicos da Água/análise
7.
J Antibiot (Tokyo) ; 72(9): 653-660, 2019 09.
Artigo em Inglês | MEDLINE | ID: mdl-31164714

RESUMO

A thermophilic bacterium Thermosporothrix hazakensis NBRC 105916 which belongs to the class Ktedonobacteria was investigated to explore its biosynthetic potential of secondary metabolites. UV-guided fractionation led to the identification of a new benzenoid metabolite designated ktedonoketone (6) and an α-diketone metabolite 2'-oxosattabacin (7) along with five known compounds. Compound 7 was previously described as a synthetic compound, but this is the first finding as a natural product. Compound 7 induced adipocyte differentiation at 10-20 µM and autophagy at 1-10 µM. Compound 6 showed weak inducing activity of adipocyte differentiation. The biosynthetic origin of hazakacin (3), an acyloin-type compound, was elucidated by 13C-labeled precursor-feeding experiments.


Assuntos
Produtos Biológicos/isolamento & purificação , Chloroflexi/metabolismo , Adipócitos/efeitos dos fármacos , Animais , Produtos Biológicos/química , Vias Biossintéticas , Diferenciação Celular/efeitos dos fármacos , Linhagem Celular , Camundongos , Estrutura Molecular
8.
Chemosphere ; 233: 81-91, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31170587

RESUMO

Microbial dechlorination of polychlorinated biphenyls (PCBs) in aquatic sediments may reduce the need for dredging for remediation. To better understand this biotransformation route under different geochemical conditions, the influence of sulfate on dechlorination in sediments from the Hudson River and the Grasse River spiked with two PCB mixtures (PCB 5/12, 64/71, 105/114 and 149/153/170 in Mixture 1 and PCB 5/12, 64/71, 82/97/99, 144/170 in Mixture 2) was investigated. The results showed that PCB dechlorination was partially inhibited in the sulfate-amended sediment microcosms. The rate, extent and preference of dechlorination were mainly controlled by the indigenous differences (sulfate, carbon content etc.) in sediment, but also affected by the PCB mixture composition. An increase of Dehalococcoides 16S rRNA genes coincided with the resumption of dechlorination. Dechlorination preferences were identified using a modified dechlorination pathway analysis approach. The low carbon content and high background sulfate Hudson sediment exhibited more para dechlorination targeting flanked para chlorines. The high carbon content and low background sulfate Grasse sediment preferentially removed more para-flanked meta chlorines than flanked para chlorines. The supplementation of fatty acids (acetate or a mixture of acetate, propionate and butyrate) dramatically increased PCB dechlorination in the Grasse sediment by resuming ortho-flanked meta dechlorination. Rare ortho removals were found in the Grasse sediment after adding fatty acids. This study suggests that supplementary fatty acids might be used to stimulate PCB dechlorination under sulfate reducing conditions, but the effectiveness largely depends on sediment geochemistry.


Assuntos
Recuperação e Remediação Ambiental/métodos , Ácidos Graxos/metabolismo , Sedimentos Geológicos/química , Bifenilos Policlorados/metabolismo , Sulfatos/metabolismo , Poluentes Químicos da Água/metabolismo , Biodegradação Ambiental , Chloroflexi/genética , Chloroflexi/metabolismo , Sedimentos Geológicos/microbiologia , Halogenação , New York , RNA Ribossômico 16S/genética , Rios
9.
Environ Pollut ; 252(Pt A): 296-304, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31158658

RESUMO

Natural attenuation of polychlorinated biphenyls (PCBs) by indigenous bacteria is an effective remediation strategy for polluted marine sediments. This study investigated the relationships between PCB concentrations in sediment pore water, humin electron transfer capacity, and potential PCB dechlorinators at eight sediment sampling sites in the southern Yellow Sea, China, with differential PCB contamination. Station A2 showed the highest PCB concentration (453.16 ng L-1 for seven indicator PCBs), especially of less chlorinated PCB congeners (≤5 Cl atoms), humin redox activity, and Dehalococcoides abundance (p < 0.05). Statistical analyses revealed a highly positive correlation between Dehalococcoides abundance and PCB concentration (r = 0.836, p < 0.05) and the electron shuttling ability of humins (r = 0.952, p < 0.01), whereas this was not observed for total bacteria and other potential PCB dechlorinators, e.g., Dehalobacter and Dehalogenimonas. Based on these results, Dehalococcoides might play an important role in the in situ reductive dechlorination of PCBs involving humins in marine sediments, and the natural microbial PCB attenuation capacity at station A2 was high. Chemical characterizations, electrochemical properties, and Fourier transform infrared analysis suggested that humins at station A2 had the highest electron transfer capacity. Furthermore, quinones are likely to be the functional groups that shuttle electrons during PCB dechlorination. Overall, this study provides a useful foundation for evaluating the natural microbial attenuation potential and fates of PCBs in marine sediments and for determining the role of humins as redox mediators in in situ PCB dechlorination by putative indigenous dechlorinators.


Assuntos
Biodegradação Ambiental , Chloroflexi/metabolismo , Sedimentos Geológicos/química , Substâncias Húmicas/análise , Bifenilos Policlorados/análise , China , Chloroflexi/classificação , Poluentes Ambientais/análise , Halogenação , Oxirredução
10.
ISME J ; 13(7): 1801-1813, 2019 07.
Artigo em Inglês | MEDLINE | ID: mdl-30872805

RESUMO

Most aerobic bacteria exist in dormant states within natural environments. In these states, they endure adverse environmental conditions such as nutrient starvation by decreasing metabolic expenditure and using alternative energy sources. In this study, we investigated the energy sources that support persistence of two aerobic thermophilic strains of the environmentally widespread but understudied phylum Chloroflexi. A transcriptome study revealed that Thermomicrobium roseum (class Chloroflexia) extensively remodels its respiratory chain upon entry into stationary phase due to nutrient limitation. Whereas primary dehydrogenases associated with heterotrophic respiration were downregulated, putative operons encoding enzymes involved in molecular hydrogen (H2), carbon monoxide (CO), and sulfur compound oxidation were significantly upregulated. Gas chromatography and microsensor experiments showed that T. roseum aerobically respires H2 and CO at a range of environmentally relevant concentrations to sub-atmospheric levels. Phylogenetic analysis suggests that the hydrogenases and carbon monoxide dehydrogenases mediating these processes are widely distributed in Chloroflexi genomes and have probably been horizontally acquired on more than one occasion. Consistently, we confirmed that the sporulating isolate Thermogemmatispora sp. T81 (class Ktedonobacteria) also oxidises atmospheric H2 and CO during persistence, though further studies are required to determine if these findings extend to mesophilic strains. This study provides axenic culture evidence that atmospheric CO supports bacterial persistence and reports the third phylum, following Actinobacteria and Acidobacteria, to be experimentally shown to mediate the biogeochemically and ecologically important process of atmospheric H2 oxidation. This adds to the growing body of evidence that atmospheric trace gases are dependable energy sources for bacterial persistence.


Assuntos
Monóxido de Carbono/metabolismo , Chloroflexi/metabolismo , Genoma Bacteriano/genética , Hidrogênio/metabolismo , Transcriptoma , Aldeído Oxirredutases/genética , Aldeído Oxirredutases/metabolismo , Atmosfera , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Chloroflexi/genética , Transporte de Elétrons/genética , Metabolismo Energético , Gases , Hidrogenase/genética , Hidrogenase/metabolismo , Complexos Multienzimáticos/genética , Complexos Multienzimáticos/metabolismo , Oxirredução , Filogenia
11.
FEMS Microbiol Lett ; 366(5)2019 03 01.
Artigo em Inglês | MEDLINE | ID: mdl-30801645

RESUMO

In this article, we present the description of a novel mesophilic phototrophic Chloroflexi bacterium, 'Candidatus Viridilinea mediisalina' Kir15-3F. We have isolated an anaerobic, highly enriched culture of this bacterium from the Kiran soda lake (Siberia) and optimized its cultivation. Metagenomic sequencing revealed that 'Ca. Viridilinea mediisalina' Kir15-3F is a bacteriochlorophyll-containing Chloroflexi bacterium in the enrichment culture. Fluorescent in situ hybridisation demonstrated a link between the phenotype described here and the 'Ca. Viridilinea mediisalina' Kir15-3F genome. Spectrophotometry and high-performance liquid chromatography analyses showed the presence of bacteriochlorophylls d, c and a, as well as lycopene, γ-carotene and ß-carotene. Transmission electron microscopy showed chlorosomes, gas vesicles, polyhydroxyalkanoate-like and polyphosphate-like granules. Our results illustrated that 'Ca. Viridilinea mediisalina' Kir15-3F is an alkaliphilic, salt-tolerant, obligately mesophilic, anaerobic, phototrophic bacterium. The genome sequences lack genes of the Calvin cycle and a sulphide:quinone reductase gene for sulphide oxidation. Owing to the lack of an axenic culture and based on the genomic and phenotypic data, we have presented the description of the bacterium in the Candidatus category.


Assuntos
Chloroflexi/classificação , Chloroflexi/metabolismo , Lagos/microbiologia , Processos Fototróficos , Bacterioclorofilas/análise , Carotenoides/análise , Chloroflexi/citologia , Chloroflexi/fisiologia , DNA Bacteriano/genética , Genoma Bacteriano/genética , Lagos/química , Metagenômica , Filogenia , RNA Ribossômico 16S/genética , Sais/metabolismo , Análise de Sequência de DNA , Sibéria , Microbiologia da Água
12.
Artigo em Inglês | MEDLINE | ID: mdl-30600760

RESUMO

This study demonstrates a combined field method accurately assessing the extent of trichloroethylene (TCE) reductive dechlorination activity and the mass fraction of its by-products. A combined method of injecting a known concentration of 1,1,2-trichloro-2-fluoroethene (TCFE) as a TCE bio-surrogate and a data processing technique of forced mass balance (FMB), considering the sorption effect on the mass fraction of chloroethene was evaluated by performing soil column and field bioaugmentation tests. In the soil column test, the FMB resulted in the mass fraction of 6% TCE, 48.3% cis-1,2-dichloroethene, 18.5% vinyl chloride and 27.2% ethylene. In the field bioaugmentation test, TCFE showed equivalent dechlorination pathways of TCE. The mass fractions estimated by FMB were very similar to those observed in the soil column bioaugmentation tests: 4.5% TCFE, 57.1% 1,2-dichloro-1-fluoroethene, 12% 1-chloro-1-fluoroethene and 26.4% fluoroethene (FE). The FMB method gave ∼50% higher mass fraction for more chlorinated ethenes (i.e., TCFE) and ∼10% lower mass fraction of less chlorinated ethenes (i.e., FE) than those considering only the aqueous concentrations of chlorofluoroethenes. A combined method of TCFE and FMB that could accurately estimate both the extent of dechlorination activities and mass distribution of TCE reductive dechlorination would be highly useful.


Assuntos
Monitoramento Ambiental/métodos , Água Subterrânea/química , Água Subterrânea/microbiologia , Tricloroetileno/análise , Poluentes Químicos da Água/análise , Poços de Água , Biodegradação Ambiental , Chloroflexi/crescimento & desenvolvimento , Chloroflexi/metabolismo , Modelos Teóricos , Projetos Piloto , República da Coreia , Fatores de Tempo
13.
Sci Total Environ ; 648: 422-429, 2019 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-30121041

RESUMO

Chlorinated ethanes are frequent groundwater contaminants but compound specific isotope analysis (CSIA) has been scarcely applied to investigate their degradation pathways. In this study, dual carbon and chlorine isotope fractionation was used to investigate for the first time the anoxic biodegradation of 1,1,2-trichloroethane (1,1,2-TCA) using a Dehalogenimonas-containing culture. The isotopic fractionation values obtained for the biodegradation of 1,1,2-TCA were ɛC = -6.9 ±â€¯0.4‰ and ɛCl = -2.7 ±â€¯0.3‰. The detection of vinyl chloride (VC) as unique byproduct and a closed carbon isotopic mass balance corroborated that dichloroelimination was the degradation pathway used by this strain. Combining the values of δ13C and δ37Cl resulted in a dual element C-Cl isotope slope of Λ = 2.5 ±â€¯0.2‰. Investigation of the apparent kinetic isotope effects (AKIEs) expected for cleavage of a CCl bond showed an important masking of the intrinsic isotope fractionation. Theoretical calculation of Λ suggested that dichloroelimination of 1,1,2-TCA was taking place via simultaneous cleavage of two CCl bonds (concerted reaction mechanism). The isotope data obtained in this study can be useful to monitor natural attenuation of 1,1,2-TCA via dichloroelimination and provide insights into the source and fate of VC in contaminated groundwaters.


Assuntos
Isótopos de Carbono/análise , Cloro/análise , Chloroflexi/metabolismo , Isótopos/análise , Tricloroetanos/metabolismo , Eliminação de Resíduos Líquidos/métodos , Poluentes Químicos da Água/metabolismo , Biodegradação Ambiental , Fracionamento Químico
14.
Appl Microbiol Biotechnol ; 103(3): 1511-1522, 2019 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-30539258

RESUMO

Conductive iron oxides (CIO) have been proved recently to facilitate the anaerobic microbial syntrophy based on the direct interspecies electron transfer (DIET) in batch experiments. However, the effect of CIO was always insignificant in anaerobic digestion (AD) reactor especially when the DIET-based syntrophic partners were absent. In this study, the effect of magnetite on performance of AD system with sucrose as a sole carbon source was investigated, but limited enhancement was achieved during the first 36-day operation. The short-term effect of ethanol addition was further studied in the magnetite-amended AD reactor, and results showed that the AD reactor with 10gFe/L micro-sized magnetite (R3) achieved higher performance of COD removal and methane proportion compared with the other reactors (R1 without magnetite; R2 with 2gFe/L micro-sized magnetite; R4 with 2gFe/L nano-sized magnetite). Meanwhile, the pyridoxine in extracellular polymeric substances (EPS) and conductivity of anaerobic sludge from R3 increased more significantly than those of the others. Analysis of high-throughput sequencing indicated that the abundance of archaea increased in sludge from R3 and Methanosarcina responsible for DIET was dominant (63.64%). Additionally, the abundance of potential electroactive bacteria Chloroflexi in R3 was 7.57-fold, 3.61-fold and 7.37-fold as that of R1, R2 and R4, respectively. These results demonstrated that the electroactive microbes and methanogens could be enriched efficiently in anaerobic sludge via synergetic effect of magnetite addition and ethanol short-term stimulation.


Assuntos
Anaerobiose/efeitos dos fármacos , Chloroflexi/metabolismo , Etanol/farmacologia , Óxido Ferroso-Férrico/farmacologia , Methanosarcina/metabolismo , Esgotos/microbiologia , Reatores Biológicos/microbiologia , Chloroflexi/crescimento & desenvolvimento , Transporte de Elétrons/efeitos dos fármacos , Transporte de Elétrons/fisiologia , Methanosarcina/crescimento & desenvolvimento , Piridoxina/análise , Esgotos/química , Sacarose/metabolismo
15.
Ecotoxicol Environ Saf ; 170: 446-452, 2019 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-30553922

RESUMO

Vertical up-flow constructed wetlands (CWs) with manganese ore (Mn ore) as media (M-CWs) were developed to treat simulated polluted river water. The results showed that the average removal efficiencies for NH4-N, NO3-N, TN and TP were 91.74%, 83.29%, 87.47% and 65.12% in M-CWs, respectively, which were only 79.12%, 72.90%, 75.85% and 43.23% in the CWs without Mn ore (C-CWs). Nutrient mass balance showed that nitrogen (N) removal was improved by enhanced microbial processes, media storage and plant uptake in M-CWs. Moreover, almost 50% of phosphorus (P) was retained by media storage because of the adsorption processes on Mn ore. It was found that addition of Mn ore enhanced denitrification as the relative abundance of denitrifying bacteria increased. The produced Mn(II) and more abundant Gammaproteobacteria confirmed alternative N removal pathways including anoxic nitrification coupled to Mn ore reduction and denitrification using Mn(II) as electron donor. Mn(II) concentration in the effluent of M-CWs was below the drinking water limit of 0.1 mg/L, which makes them environmentally-friendly.


Assuntos
Manganês/química , Nitrogênio/análise , Fósforo/análise , Poluentes Químicos da Água/análise , Áreas Alagadas , Acidobacteria/isolamento & purificação , Acidobacteria/metabolismo , Bacteroidetes/isolamento & purificação , Bacteroidetes/metabolismo , Chloroflexi/isolamento & purificação , Chloroflexi/metabolismo , Desnitrificação , Gammaproteobacteria/isolamento & purificação , Gammaproteobacteria/metabolismo , Microbiota , Modelos Teóricos , Proteobactérias/isolamento & purificação , Proteobactérias/metabolismo , Rios/química , Verrucomicrobia/isolamento & purificação , Verrucomicrobia/metabolismo
16.
FEMS Microbiol Ecol ; 95(1)2019 01 01.
Artigo em Inglês | MEDLINE | ID: mdl-30339222

RESUMO

Chloroethenes are common groundwater and soil contaminants due to extensive historic utilization and inappropriate discharge. The tendency for chloroethenes to become sequestered as dense non-aqueous phase liquids (DNAPL)-a point source to groundwater contamination and causing high concentrations of chloroethenes in proximal aquifers poses a great challenge for remediation of chloroethene contaminated sites. In this study, we report isolation and characterization of a Dehalococcoides mccartyi strain 11G which couples growth with reductive dechlorination of trichloroethenes (TCE), dichloroethene (DCE) isomers and vinyl chloride (VC) to ethene at a growth yield ranging from 2.47 ± 0.23 × 108 to 5.64 ± 0.43 × 108 cells/µmoles Cl- released and co-metabolically dechlorinates tetrachloroethene (PCE) in the presence of TCE. Compared with previous D. mccartyi strains showing dechlorination of TCE at up to 2.0 mM, strain 11G is distinguished by its capacity to dechlorinate chloroethenes at initial concentrations of DCE isomers as high as 4 mM and TCE as high as 3.5 mM to ethene. Bioaugmentation of a contaminated microcosm with strain 11G resulted in complete detoxification of a mixture of 5 mM chloroethenes (2.5 mM of each TCE and cis-DCE) after 40 days. Strain 11G is a promising candidate for in situ bioremediation of high-concentration-chloroethene contaminated sites.


Assuntos
Chloroflexi/metabolismo , Cloreto de Vinil/metabolismo , Biodegradação Ambiental , Chloroflexi/genética , Chloroflexi/crescimento & desenvolvimento , Chloroflexi/isolamento & purificação , Água Subterrânea/química , Halogenação , Poluentes do Solo/química , Poluentes do Solo/metabolismo , Tetracloroetileno/química , Tetracloroetileno/metabolismo , Tricloroetileno/química , Tricloroetileno/metabolismo , Cloreto de Vinil/química , Poluentes da Água/química , Poluentes da Água/metabolismo
17.
Can J Microbiol ; 64(12): 992-1003, 2018 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-30338698

RESUMO

The phylum Chloroflexi is phylogenetically diverse and is a deeply branching lineage of bacteria that express a broad spectrum of physiological and metabolic capabilities. Members of the order Ktedonobacteriales, including the families Ktedonobacteriaceae, Thermosporotrichaceae, and Thermogemmatisporaceae, all have flexible aerobic metabolisms capable of utilizing a wide range of carbohydrates. A number of species within these families are considered cellulolytic and are capable of using cellulose as a sole carbon and energy source. In contrast, Ktedonobacter racemifer, the type strain of the order, does not appear to possess this cellulolytic phenotype. In this study, we confirmed the ability of Thermogemmatispora sp. strain T81 to hydrolyze cellulose, determined the whole-genome sequence of Thermogemmatispora sp. T81, and using comparative bioinformatics analyses, identified genes encoding putative carbohydrate-active enzymes (CAZymes) in the Thermogemmatispora sp. T81, Thermogemmatispora onikobensis, and Ktedonobacter racemifer genomes. Analyses of the Thermogemmatispora sp. T81 genome identified 64 CAZyme gene sequences belonging to 57 glycoside hydrolase families. The genome of Thermogemmatispora sp. T81 encodes 19 genes for putative extracellular CAZymes, similar to the number of putative extracellular CAZymes identified in T. onikobensis (17) and K. racemifer (17), despite K. racemifer not possessing a cellulolytic phenotype. These results suggest that these members of the order Ktedonobacteriales may use a broader range of carbohydrate polymers than currently described.


Assuntos
Metabolismo dos Carboidratos , Chloroflexi/metabolismo , Celulose/metabolismo , Chloroflexi/genética , Biologia Computacional
18.
Appl Microbiol Biotechnol ; 102(23): 10285-10297, 2018 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-30276715

RESUMO

Knowledge of connections between operational conditions, process stability, and microbial community dynamics is essential to enhance anaerobic digestion (AD) process efficiency and management. In this study, the detailed temporal effects of a sudden glycerol-based organic overloading on the AD microbial community and process imbalance were investigated in two replicate anaerobic digesters by a time-intensive sampling scheme. The microbial community time response to the overloading event was shorter than the shifts of reactor performance parameters. An increase in bacterial community dynamics and in the abundances of several microbial taxa, mainly within the Firmicutes, Tenericutes, and Chloroflexi phyla and Methanoculleus genera, could be detected prior to any shift on the reactor operational parameters. Reactor acidification already started within the first 24 h of the shock and headed the AD process to total inhibition in 72 h alongside with the largest shifts on microbiome, mostly the increase of Anaerosinus sp. and hydrogenotrophic methanogenic Archaea. In sum, this work proved that AD microbial community reacts very quickly to an organic overloading and some shifts occur prior to alterations on the performance parameters. The latter is very interesting as it can be used to improve AD process management protocols.


Assuntos
Biomassa , Reatores Biológicos/microbiologia , Microbiota , Anaerobiose , Archaea/classificação , Archaea/isolamento & purificação , Chloroflexi/classificação , Chloroflexi/metabolismo , Biologia Computacional , DNA Bacteriano/genética , Firmicutes/classificação , Firmicutes/metabolismo , Sequenciamento de Nucleotídeos em Larga Escala , Hibridização in Situ Fluorescente , Microbiologia Industrial , Methanomicrobiaceae/classificação , Methanomicrobiaceae/metabolismo , Tenericutes/classificação , Tenericutes/metabolismo
19.
Environ Pollut ; 243(Pt A): 766-776, 2018 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-30228068

RESUMO

Trichloroethylene (TCE) is one of the most common groundwater contaminants in the United States; however clean-up efforts are a challenge due to its physical and chemical properties. TCE and several of its degradation products were detected in the groundwater of the Beaver Dam Road Landfill site (Beltsville, MD) at concentrations above accepted maximum contaminant levels. A permeable reactive barrier (i.e., biowall) was installed to remediate the groundwater. Microbial infiltration and colonization of the biowall with native site bacteria was expected to occur. An array of molecular biological tools was applied to survey the microbial community for presence of organohalide-respiring microorganisms at the site. Microorganisms belonging to methanogens, acetogens, sulfate-reducing bacteria, and chlorinated aliphatic hydrocarbon-metabolizing bacteria were identified, thus making way for the application of the microbial populations in the biowall bioaugmentation efforts. In concomitant laboratory studies, molecular approaches were used to monitor continuously-fed column reactors containing saturated biowall material spiked with a commercially-available, Dehalococcoides-containing culture (SDC-9), with or without zero-valent iron (ZVI) shavings. The column without ZVI had the highest abundance of Dehalococcoides spp. (2.7 × 106 cells g-1 material, S.D. = 3.8 × 105 cells g-1 material), while the addition of ZVI did not affect the overall population. Although the addition of ZVI and biostimulation did change ratios of the Dehalococcoides strains, the results suggests that if ZVI would be applied as a biowall material amendment, biostimulation would not be required to maintain a Dehalococcoides population. These experimental results will be utilized in future remediation and/or biowall expansion plans to utilize the natural resources most effectively at the biowall site.


Assuntos
Biodegradação Ambiental , Chloroflexi/metabolismo , Água Subterrânea/química , Tricloroetileno/metabolismo , Poluentes Químicos da Água/metabolismo , Halogenação , Ferro/química , Poluentes Químicos da Água/análise
20.
Appl Environ Microbiol ; 84(21)2018 11 01.
Artigo em Inglês | MEDLINE | ID: mdl-30171004

RESUMO

Reductive dehalogenation mediated by organohalide-respiring bacteria plays a critical role in the global cycling of organohalides. Nonetheless, information on the dehalogenation enantioselectivity of organohalide-respiring bacteria remains limited. In this study, we report the enantioselective dechlorination of chiral polychlorinated biphenyls (PCBs) by Dehalococcoides mccartyi CG1. CG1 preferentially removed halogens from the (-)-enantiomers of the three major environmentally relevant chiral PCBs (PCB174, PCB149, and PCB132), and the enantiomer compositions of the dechlorination products depended on their parent organohalides. The in vitro assays with crude cell extracts or concentrated whole cells and the in vivo experiments with living cells showed similar enantioselectivities, in contrast with the distinct enantiomeric enrichment factors (εER) of the substrate chiral PCBs. Additionally, these results suggest that concentrated whole cells might be an alternative to crude cell extracts in in vitro tests of reductive dehalogenation activities. The enantioselective dechlorination of other chiral PCBs that we resolved via gas chromatography further confirmed the preference of CG1 for the (-)-enantiomers.IMPORTANCE A variety of agrochemicals and pharmaceuticals are chiral. Due to the enantioselectivity in biological processes, enantiomers of chiral compounds may have different environmental occurrences, fates, and ecotoxicologies. Many chiral organohalides exist in anaerobic or anoxic soils and sediments, and organohalide-respiring bacteria play a major role in the environmental attenuation and global cycling of these chiral organohalides. Therefore, it is important to investigate the dehalogenation enantioselectivity of organohalide-respiring bacteria. This study reports the discovery of enantioselective dechlorination of chiral PCBs by Dehalococcoides mccartyi CG1, which provides insights into the dehalogenation enantioselectivity of Dehalococcoides and may shed light on future PCB bioremediation efforts to prevent enantioselective biological side effects.


Assuntos
Chloroflexi/metabolismo , Bifenilos Policlorados/química , Bifenilos Policlorados/metabolismo , Biodegradação Ambiental , Chloroflexi/química , Cromatografia Gasosa , Halogenação , Estereoisomerismo , Poluentes Químicos da Água/química , Poluentes Químicos da Água/metabolismo
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