RESUMO
Hydrogen-releasing substrates can stimulate the reductive dechlorination of trichloroethene (TCE) mediated by organohalide-respiring bacteria (OHRB) at contaminated sites. However, how the substrate affects microbiome assembly and the accompanying influences on the growth of OHRB and reductive TCE dechlorination remains unclear. We evaluated the effects of microbial community structures and potential functions on the reductive dechlorination of TCE in three anaerobic reactors with acetate, soybean oil, or molasses as the substrate and no cobalamin or amino acid supplementation. The molasses-fed reactor exhibited superior performance and dechlorination of TCE loadings to ethene, and the oil-fed reactor exhibited a high growth rate of the key OHRB, Dehalococcoides. This finding suggests an effect of the substrate on reductive dechlorination and the growth of Dehalococcoides. The three reactors developed distinct microbial community structures and the predicted metagenomes were distinguished on the basis of vitamin and amino acid metabolisms as well as fermentation pathways. In addition to the diversified hydrogen-producing pathways, the molasses-induced microbiome exhibited high potential to synthesize the cobalamin, which may account for its high Dehalococcoides activity and thus effective dechlorination performance. The substrate dependence of microbiomes may provide insight into strategies of exogenous amino acid supplementation to benefit Dehalococcoides growth. This study adds novel insight into the interplay of hydrogen-releasing substrates and OHRB. The results may contribute to the development of tailored and cost-effective management for the reductive dechlorination of chlorinated solvents in bioremediation.
Assuntos
Chloroflexi , Microbiota , Tricloroetileno , Biodegradação Ambiental , Chloroflexi/genética , FermentaçãoRESUMO
Climate change is altering the frequency and severity of drought events. Recent evidence indicates that drought may produce legacy effects on soil microbial communities. However, it is unclear whether precedent drought events lead to ecological memory formation, i.e., the capacity of past events to influence current ecosystem response trajectories. Here, we utilize a long-term field experiment in a mountain grassland in central Austria with an experimental layout comparing 10 years of recurrent drought events to a single drought event and ambient conditions. We show that recurrent droughts increase the dissimilarity of microbial communities compared to control and single drought events, and enhance soil multifunctionality during drought (calculated via measurements of potential enzymatic activities, soil nutrients, microbial biomass stoichiometry and belowground net primary productivity). Our results indicate that soil microbial community composition changes in concert with its functioning, with consequences for soil processes. The formation of ecological memory in soil under recurrent drought may enhance the resilience of ecosystem functioning against future drought events.
Assuntos
Secas/estatística & dados numéricos , Microbiota/fisiologia , Microbiologia do Solo , Solo/química , Água/análise , Acidobacteria/classificação , Acidobacteria/genética , Acidobacteria/isolamento & purificação , Actinobacteria/classificação , Actinobacteria/genética , Actinobacteria/isolamento & purificação , Altitude , Áustria , Bacteroidetes/classificação , Bacteroidetes/genética , Bacteroidetes/isolamento & purificação , Biomassa , Carbono/análise , Chloroflexi/classificação , Chloroflexi/genética , Chloroflexi/isolamento & purificação , Pradaria , Humanos , Nitrogênio/análise , Fósforo/análise , Planctomycetales/classificação , Planctomycetales/genética , Planctomycetales/isolamento & purificação , Proteobactérias/classificação , Proteobactérias/genética , Proteobactérias/isolamento & purificação , Enxofre/análise , Verrucomicrobia/classificação , Verrucomicrobia/genética , Verrucomicrobia/isolamento & purificaçãoRESUMO
Chloroethenes are common soil and groundwater pollutants. Their dechlorination is impacted by environmental factors, such as the presence of metal ions. We here investigated the effect of ferrous iron on bacterial reductive dechlorination of chloroethenes and on methanogen community. Reductive dechlorination of tetrachloroethene was assayed with a groundwater sample originally containing 6.3 × 103 copies mL-1 of Dehalococcoides 16S rRNA gene and 2 mg L-1 of iron. Supplementation with 28 mg L-1 of ferrous iron enhanced the reductive dechlorination of cis-dichloroethene (cis-DCE) and vinyl chloride in the presence of methanogens. The supplementation shortened the time required for complete dechlorination of 1 mg L-1 of tetrachloroethene to ethene and ethane from 84 to 49 d. Methanogens, such as Candidatus 'Methanogranum', Methanomethylovorans and Methanocorpusculum, were significantly more abundant in iron-supplemented cultures than in non-supplemented cultures (P < 0.01). Upon methanogen growth inhibition by 2-bromoethanesulfonate and in the absence of iron supplementation, cis-DCE was not dechlorinated. Further, iron supplementation induced 71.3% dechlorination of cis-DCE accompanied by an increase in Dehalococcoides 16S rRNA and dehalogenase vcrA gene copies but not dehalogenase tceA gene copies. These observations highlight the cooperative effect of iron and methanogens on the reductive dechlorination of chloroethenes by Dehalococcoides spp.
Assuntos
Chloroflexi , Microbiota , Tetracloroetileno , Cloreto de Vinil , Biodegradação Ambiental , Chloroflexi/genética , Suplementos Nutricionais , Ferro , RNA Ribossômico 16S/genéticaRESUMO
While microbial communities in the human body (microbiota) are now commonly associated with health and disease in industrialised populations, we know very little about how these communities co-evolved and changed with humans throughout history and deep prehistory. We can now examine these communities by sequencing ancient DNA preserved within calcified dental plaque (calculus), providing insights into the origins of disease and their links to human history. Here, we examine ancient DNA preserved within dental calculus samples and their associations with two major cultural periods in Japan: the Jomon period hunter-gatherers approximately 3000 years before present (BP) and the Edo period agriculturalists 400-150 BP. We investigate how human oral microbiomes have changed in Japan through time and explore the presence of microorganisms associated with oral diseases (e.g. periodontal disease, dental caries) in ancient Japanese populations. Finally, we explore oral microbial strain diversity and its potential links to ancient demography in ancient Japan by performing phylogenomic analysis of a widely conserved oral species-Anaerolineaceae oral taxon 439. This research represents, to our knowledge, the first study of ancient oral microbiomes from Japan and demonstrates that the analysis of ancient dental calculus can provide key information about the origin of non-infectious disease and its deep roots with human demography. This article is part of the theme issue 'Insights into health and disease from ancient biomolecules'.
Assuntos
Chloroflexi/genética , Cárie Dentária/história , Genoma Bacteriano , Microbiota , Boca/microbiologia , Doenças Periodontais/história , Chloroflexi/classificação , Demografia , Cárie Dentária/microbiologia , História do Século XVII , História do Século XVIII , História do Século XIX , História Antiga , Humanos , Japão , Doenças Periodontais/microbiologia , Filogenia , Dinâmica PopulacionalRESUMO
The bacteria inhabiting brackish lake environments in arid or semi-arid regions have not been thoroughly identified. In this study, the 454 pyrosequencing method was used to study the sedimentary bacterial community composition (BCC) and diversity in Lake Bosten, which is located in the arid regions of northwestern China. A total of 210,233 high-quality sequence reads and 8,427 operational taxonomic units (OTUs) were successfully obtained from 20 selected sediment samples. The samples were quantitatively dominated by members of Proteobacteria (34.1% ± 11.0%), Firmicutes (21.8% ± 21.9%) and Chloroflexi (13.8% ± 5.2%), which accounted for more than 69% of the bacterial sequences. The results showed that (i) Lake Bosten had significant spatial heterogeneity, and TOC(total organic carbon), TN(total nitrogen) and TP(total phosphorus) were the most important contributors to bacterial diversity; (ii) there was lower taxonomic richness in Lake Bosten, which is located in an arid region, than in reference lakes in eutrophic floodplains and marine systems; and (iii) there was a low percentage of dominant species in the BCC and a high percentage of unidentified bacteria. Our data help to better describe the diversity and distribution of bacterial communities in contaminated brackish lakes in arid regions and how microbes respond to environmental changes in these stable inland waters in arid or semi-arid regions.
Assuntos
Chloroflexi/isolamento & purificação , Ecossistema , Firmicutes/isolamento & purificação , Lagos/microbiologia , Proteobactérias/isolamento & purificação , Biodiversidade , China , Chloroflexi/genética , DNA Bacteriano/química , DNA Bacteriano/metabolismo , Firmicutes/genética , Sedimentos Geológicos/microbiologia , Fósforo/química , Fósforo/metabolismo , Proteobactérias/genética , Estações do Ano , Análise de Sequência de DNA/métodos , Qualidade da ÁguaRESUMO
Microorganisms play important roles in soil improvement. Therefore, clarifying the contribution of environmental factors in shaping the microbial community structure is beneficial to improve soil fertility in karst rocky desertification areas. Here, the bacterial community structures of eight rhizospheric soil samples collected from perennial fruit plantations were analysed using an Illumina HiSeq2500 platform. The diversity and abundance of bacteria in rocky desertification areas were significantly lower than those in non-rocky desertification areas, while the bacterial community structure was not significantly different between root surface and non-root surface soils in the same rhizospheric soil samples. Proteobacteria predominated in rocky desertification areas, while Actinobacteria predominated in non-rocky desertification areas. Correlation analysis revealed that water-soluble phosphorus content (r2 = 0.8258), latitude (r2 = 0.7556), altitude (r2 = 0.7501), and the age of fruit trees (r2 = 0.7321) were positively correlated with the bacterial community structure, while longitude, pH, and total phosphorus content did not significantly influence the soil bacterial community structure. As water-soluble phosphorus content is derived from insoluble phosphorus minerals, supplementing phosphorus-solubilising bacteria to soils in rocky desertification areas is a feasible strategy for accelerating the dissolution of insoluble phosphorus minerals and improving agricultural production and environment ecology.
Assuntos
Microbiota/genética , Microbiologia do Solo , Solo/química , Árvores/microbiologia , Acidobacteria/classificação , Acidobacteria/genética , Acidobacteria/isolamento & purificação , Actinobacteria/classificação , Actinobacteria/genética , Actinobacteria/isolamento & purificação , Agricultura/métodos , Bacteroidetes/classificação , Bacteroidetes/genética , Bacteroidetes/isolamento & purificação , China , Chloroflexi/classificação , Chloroflexi/genética , Chloroflexi/isolamento & purificação , Conservação dos Recursos Naturais/legislação & jurisprudência , DNA Bacteriano/genética , Firmicutes/classificação , Firmicutes/genética , Firmicutes/isolamento & purificação , Humanos , Concentração de Íons de Hidrogênio , Fósforo/química , Fósforo/metabolismo , Proteobactérias/classificação , Proteobactérias/genética , Proteobactérias/isolamento & purificação , Rizosfera , Árvores/fisiologia , Água/metabolismoRESUMO
Control of common scab disease can be reached by resistant cultivars or suppressive soils. Both mechanisms are likely to translate into particular potato microbiome profiles, but the relative importance of each is not known. Here, microbiomes of bulk and tuberosphere soil and of potato periderm were studied in one resistant and one susceptible cultivar grown in a conducive and a suppressive field. Disease severity was suppressed similarly by both means yet, the copy numbers of txtB gene (coding for a pathogenicity determinant) were similar in both soils but higher in periderms of the susceptible cultivar from conducive soil. Illumina sequencing of 16S rRNA genes for bacteria (completed by 16S rRNA microarray approach) and archaea, and of 18S rRNA genes for micro-eukarytes showed that in bacteria, the more important was the effect of cultivar and diversity decreased from resistant cultivar to bulk soil to susceptible cultivar. The major changes occurred in proportions of Actinobacteria, Chloroflexi, and Proteobacteria. In archaea and micro-eukaryotes, differences were primarily due to the suppressive and conducive soil. The effect of soil suppressiveness × cultivar resistance depended on the microbial community considered, but differed also with respect to soil and plant nutrient contents particularly in N, S and Fe.
Assuntos
Actinobacteria/crescimento & desenvolvimento , Archaea/crescimento & desenvolvimento , Suscetibilidade a Doenças/imunologia , Doenças das Plantas/microbiologia , Microbiologia do Solo , Solanum tuberosum/microbiologia , Actinobacteria/classificação , Actinobacteria/genética , Actinobacteria/patogenicidade , Archaea/classificação , Archaea/genética , Archaea/patogenicidade , Chloroflexi/classificação , Chloroflexi/genética , Chloroflexi/crescimento & desenvolvimento , Chloroflexi/patogenicidade , Produtos Agrícolas , Resistência à Doença/efeitos dos fármacos , Células Eucarióticas/metabolismo , Técnicas de Genotipagem , Ferro/metabolismo , Ferro/farmacologia , Microbiota/genética , Nitrogênio/metabolismo , Nitrogênio/farmacologia , Doenças das Plantas/imunologia , Proteobactérias/classificação , Proteobactérias/genética , Proteobactérias/crescimento & desenvolvimento , Proteobactérias/patogenicidade , RNA Ribossômico 16S/genética , RNA Ribossômico 18S/genética , Solanum tuberosum/efeitos dos fármacos , Solanum tuberosum/imunologia , Enxofre/metabolismo , Enxofre/farmacologia , Fatores de Virulência/genética , Fatores de Virulência/metabolismoRESUMO
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 , RiosRESUMO
The bioremediation potential of an aquifer contaminated with tetrachloroethene (PCE) was assessed by combining hydrogeochemical data of the site, microcosm studies, metabolites concentrations, compound specific-stable carbon isotope analysis and the identification of selected reductive dechlorination biomarker genes. The characterization of the site through 10 monitoring wells evidenced that leaked PCE was transformed to TCE and cis-DCE via hydrogenolysis. Carbon isotopic mass balance of chlorinated ethenes pointed to two distinct sources of contamination and discarded relevant alternate degradation pathways in the aquifer. Application of specific-genus primers targeting Dehalococcoides mccartyi species and the vinyl chloride-to-ethene reductive dehalogenase vcrA indicated the presence of autochthonous bacteria capable of the complete dechlorination of PCE. The observed cis-DCE stall was consistent with the aquifer geochemistry (positive redox potentials; presence of dissolved oxygen, nitrate, and sulphate; absence of ferrous iron), which was thermodynamically favourable to dechlorinate highly chlorinated ethenes but required lower redox potentials to evolve beyond cis-DCE to the innocuous end product ethene. Accordingly, the addition of lactate or a mixture of ethanol plus methanol as electron donor sources in parallel field-derived anoxic microcosms accelerated dechlorination of PCE and passed cis-DCE up to ethene, unlike the controls (without amendments, representative of field natural attenuation). Lactate fermentation produced acetate at near-stoichiometric amounts. The array of techniques used in this study provided complementary lines of evidence to suggest that enhanced anaerobic bioremediation using lactate as electron donor source is a feasible strategy to successfully decontaminate this site.
Assuntos
Biodegradação Ambiental/efeitos dos fármacos , Água Subterrânea/química , Tetracloroetileno/análise , Bactérias/metabolismo , Isótopos de Carbono/análise , Chloroflexi/genética , Halogenação , Ácido Láctico/farmacologia , Espanha , Poluentes Químicos da Água/análiseRESUMO
The evolution of the bacterial population during formation of denitrifying phosphorus removal granular sludge was investigated using high-throughput pyrosequencing. As a result, mature granules with a compact structure were obtained in an anaerobic/aerobic/anoxic (A/O/A) sequencing batch reactor under an organic loading rate as low as 0.3kg COD/(m(3)·d). Rod-shaped microbes were observed to cover with the outer surface of granules. Besides, reliable COD and simultaneous nitrogen and phosphorus removal efficiencies were achieved over the whole operation period. MiSeq pyrosequencing analysis illustrated that both the microbial diversity and richness increased sharply during the granulation process, whereas they stayed stable after the presence of granules. Some microorganisms seemed to contribute to the formation of granules, and some were identified as functional bacterial groups responsible for constructing the biological reactor.
Assuntos
Reatores Biológicos/microbiologia , Esgotos/microbiologia , Aerobiose , Anaerobiose , Bacteroidetes/genética , Técnicas de Cultura Celular por Lotes , Biodegradação Ambiental , Chloroflexi/genética , Firmicutes/genética , Consórcios Microbianos , Interações Microbianas , Tipagem Molecular , Nitrogênio/análise , Fósforo/análise , Filogenia , Proteobactérias/genética , Esgotos/análiseRESUMO
A comprehensive study of the identity and population dynamics of filamentous bacteria in five Polish full-scale municipal wastewater treatment plants (WWTPs) with nutrients removal had been carried out for 2 years. A quantitative culture-independent, molecular method - fluorescence in situ hybridization - was applied to evaluate the structure of different filamentous bacteria populations and their temporal variations. Activated sludge was examined for the abundance of 11 groups of filamentous bacteria. On average, filaments constituted 28% of all bacteria. All samples presented a low diversity of probe-defined filamentous bacteria, usually with significant domination of Chloroflexi (with distinction to types 1851, 0803 and others) and/or Microthrix (14% and 7% of EUBmix, respectively). Haliscomenobacter hydrossis, Mycolata, Skermania piniformis and TM7 were less abundant, whereas Curvibacter, Thiothrix/021N and family Gordonia have not been detected in any of the samples. The tested WWTPs showed similarity among species found and differences in their abundance. The composition of filamentous populations was rather stable in each plant and similar to those found in other European countries. Little differences between plants were shown by multivariate analysis of variance in terms of Chloroflexi and Microthrix. No significant general correlations have been found with Pearson product-moment correlation coefficient and Spearman's rank correlation coefficient. Medium correlation strength between the presence of different filaments was recorded only for Microthrix and Skermania piniformis. Deleterious effect on settling properties of sludge (measured as sludge volume index) was found only for abundance of Microthrix; a strong linear correlation was recorded between them. However, no other correlations with wastewater and operational data were revealed.
Assuntos
Bactérias , Esgotos/microbiologia , Eliminação de Resíduos Líquidos/métodos , Bactérias/genética , Chloroflexi/genética , Interpretação Estatística de Dados , Hibridização in Situ Fluorescente , Polônia , Estações do Ano , Águas Residuárias/microbiologiaRESUMO
A thermophilic, filamentous, heterotrophic bacterium, designated strain JAD2(T), a member of an as-yet uncultivated lineage that is present and sometimes abundant in some hot springs worldwide, was isolated from sediment of Great Boiling Spring in Nevada, USA. Cells had a mean diameter of 0.3 µm and length of 4.0 µm, and formed filaments that typically ranged in length from 20 to 200 µm. Filaments were negative for the Gram stain reaction, spores were not formed and motility was not observed. The optimum temperature for growth was 72.5-75 °C, with a range of 67.5-75 °C, and the optimum pH for growth was 6.75, with a range of pH 6.5-7.75. Peptone, tryptone or yeast extract were able to support growth when supplemented with vitamins, but no growth was observed using a variety of defined organic substrates. Strain JAD2(T) was microaerophilic and facultatively anaerobic, with optimal growth at 1% (v/v) O2 and an upper limit of 8% O2. The major cellular fatty acids (>5%) were C(16â:â0), C(19â:â0), C(18â:â0), C(20â:â0) and C(19â:â1). The genomic DNA G+C content was 69.3 mol%. Phylogenetic and phylogenomic analyses using sequences of the 16S rRNA gene and other conserved genes placed JAD2(T) within the phylum Chloroflexi, but not within any existing class in this phylum. These results indicate that strain JAD2(T) is the first cultivated representative of a novel lineage within the phylum Chloroflexi, for which we propose the name Thermoflexus hugenholtzii gen. nov., sp. nov., within Thermoflexia classis nov., Thermoflexales ord. nov. and Thermoflexaceae fam. nov. The type strain of Thermoflexus hugenholtzii is JAD2(T) (â=âJCM 19131(T)â=âCCTCC AB-2014030(T)).
Assuntos
Chloroflexi/classificação , Fontes Termais/microbiologia , Filogenia , Técnicas de Tipagem Bacteriana , Composição de Bases , Chloroflexi/genética , Chloroflexi/isolamento & purificação , DNA Bacteriano/genética , Ácidos Graxos/química , Sedimentos Geológicos/microbiologia , Temperatura Alta , Dados de Sequência Molecular , Nevada , RNA Ribossômico 16S/genética , Análise de Sequência de DNARESUMO
Dehalococcoides mccartyi strains are strictly anaerobic organisms specialized to grow with halogenated compounds as electron acceptor via a respiratory process. Their genomes are among the smallest known for free-living organisms, and the embedded gene set reflects their strong specialization. Here, we briefly review main characteristics of published Dehalococcoides genomes and show how genome information together with cultivation and biochemical experiments have contributed to our understanding of Dehalococcoides physiology and biochemistry. We extend this approach by the detailed analysis of cofactor metabolism in Dehalococcoides strain CBDB1. Dehalococcoides genomes were screened for encoded proteins annotated to contain or interact with organic cofactors, and the expression of these proteins was analysed by shotgun proteomics to shed light on cofactor requirements. In parallel, cultivation experiments testing for vitamin requirements showed that cyanocobalamin (vitamin B12), thiamine and biotin were essential supplements and that cyanocobalamin could be substituted by dicyanocobinamide and dimethylbenzimidazole. Dehalococcoides genome analysis, detection of single enzymes by shotgun proteomics and inhibition studies confirmed the expression of the biosynthetic pathways for pyridoxal-5-phosphate, flavin nucleotides, folate, S-adenosylmethionine, pantothenate and nicotinic acids in strain CBDB1. Haem/cytochromes, quinones and lipoic acids were not necessary for cultivation or dechlorination activity and no biosynthetic pathways were identified in the genomes.
Assuntos
Chloroflexi/metabolismo , Coenzimas/metabolismo , Genoma Bacteriano , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Biotina/biossíntese , Biotina/metabolismo , Chloroflexi/genética , Chloroflexi/fisiologia , Coenzimas/biossíntese , Corrinoides/metabolismo , Ácido Fólico/biossíntese , Anotação de Sequência Molecular , Nitrilas/metabolismo , Compostos Organometálicos/metabolismo , Ácido Pantotênico/biossíntese , Ácido Pantotênico/metabolismo , Especificidade da Espécie , Tetra-Hidrofolato Desidrogenase/metabolismo , Tiamina/biossíntese , Tiamina/metabolismo , Vitamina B 12/biossíntese , Vitamina B 12/metabolismoRESUMO
Mixed groundwater contaminations by chlorinated volatile organic compounds (VOC) cause environmental hazards if contaminated groundwater discharges into surface waters and river floodplains. Constructed wetlands (CW) or engineered natural wetlands provide a promising technology for the protection of sensitive water bodies. We adapted a constructed wetland able to treat monochlorobenzene (MCB) contaminated groundwater to a mixture of MCB and tetrachloroethene (PCE), representing low and high chlorinated model VOC. Simultaneous treatment of both compounds was efficient after an adaptation time of 2 1/2 years. Removal of MCB was temporarily impaired by PCE addition, but after adaptation a MCB concentration decrease of up to 64% (55.3 micromol L(-1)) was observed. Oxygen availability in the rhizosphere was relatively low, leading to sub-optimal MCB elimination but providing also appropriate conditions for PCE dechlorination. PCE and metabolites concentration patterns indicated a very slow system adaptation. However, under steady state conditions complete removal of PCE inflow concentrations of 10-15 micromol L(-1) was achieved with negligible concentrations of chlorinated metabolites in the outflow. Recovery of total dechlorination metabolite loads corresponding to 100%, and ethene loads corresponding to 30% of the PCE inflow load provided evidence for complete reductive dechlorination, corroborated by the detection of Dehalococcoides sp.
Assuntos
Clorobenzenos/metabolismo , Tetracloroetileno/metabolismo , Poluentes Químicos da Água/metabolismo , Áreas Alagadas , Biodegradação Ambiental , Chloroflexi/genética , Chloroflexi/isolamento & purificação , Análise por Conglomerados , Oxirredução , Oxigênio/análise , Rizosfera , Solo/análise , Fatores de Tempo , Água/análiseRESUMO
Sunflower oil cake (SuOC) is the solid by-product from the sunflower oil extraction process and an important pollutant waste because of its high organic content. For the anaerobic digestion of SuOC three different industrial reactors were compared as inoculum sources. This was done using a biochemical methane production (BMP) test. Inoculum I was a granular biomass from an industrial reactor treating soft-drink wastewaters. Inoculum II was a flocculent biomass from a full-scale reactor treating biosolids generated in an urban wastewater treatment plant. Inoculum III was a granular biomass from an industrial reactor treating brewery wastes. The highest kinetic constant for methane production was achieved using inoculum II. The inoculum sources were analyzed through PCR amplification of 16S rRNA genes and fingerprinting before (t = 0) and after the BMP test (t = 12 days). No significant differences were found in the bacterial community fingerprints between the beginning and the end of the experiments. The bacterial and archaeal communities of inoculum II were further analyzed. The main bacteria found in this inoculum belong to Alphaproteobacteria and Chloroflexi. Of the Archaea detected, Methanomicrobiales and Methanosarcinales made up practically the whole archaeal community. The results showed the importance of selecting an appropriate inoculum in short term processes due to the fact that the major microbial constituents in the initial consortia remained stable throughout anaerobic digestion.