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1.
Water Res ; 197: 117120, 2021 Jun 01.
Artículo en Inglés | MEDLINE | ID: mdl-33862393

RESUMEN

As a clean and renewable energy, biogas is an important alternative to fossil fuels. However, the high carbon dioxide (CO2) content in biogas limits its value as a fuel. 'Biogas upgrading' is an advanced process which removes CO2 from biogas, thereby converting biogas to biomethane, which has a higher commercial value. Microbial technologies offer a sustainable and cost-effective way to upgrade biogas, removing CO2 using hydrogen (H2) as electron donor, generated by surplus electricity from renewable wind or solar energy. Hydrogenotrophic methanogens can be applied to convert CO2 with H2 to methane (CH4), or alternatively, homoacetogens can convert both CO2 and H2 into value-added chemicals. Here, we comprehensively review the current state of biogas generation and utilization, and describe the advances in biological, H2-dependent biogas upgrading technologies, with particular attention to key challenges associated with the processes, e.g., metabolic limitations, low H2 transfer rate, and finite CO2 conversion rate. We also highlight several new strategies for overcoming technical barriers to achieve efficient CO2 conversion, including process optimization to eliminate metabolic limitation, novel reactor designs to improve H2 transfer rate and utilization efficiency, and employing advanced genetic engineering tools to generate more efficient microorganisms. The insights offered in this review will promote further exploration into microbial, H2-driven biogas upgrading, towards addressing the global energy crisis and climate change associated with use of fossil fuels.


Asunto(s)
Biocombustibles , Euryarchaeota , Reactores Biológicos , Dióxido de Carbono , Hidrógeno , Metano
2.
J Environ Manage ; 288: 112363, 2021 Jun 15.
Artículo en Inglés | MEDLINE | ID: mdl-33756388

RESUMEN

This study evaluated the effects of thermal pretreatment of brewery spent grain (BSG) (by autoclave 121 °C, 1.45 atm for 30 min) on methane production (CH4). Operation temperature (31-59 °C) and substrate concentration (8.3-19.7 g BSG.L-1) factors were investigated by Response Surface Methodology (RSM) and Central Composite Design (CCD). Values ranging from 81.1 ± 2.0 to 290.1 ± 3.5 mL CH4.g-1 TVS were obtained according to operation temperature and substrate concentration variation. The most adverse condition for methanogenesis (81.1 ± 2.0 mL CH4.g-1 TVS) was at 59 °C and 14 g BSG.L-1, in which there was increase in the organic matter concentration from 173.6 ± 4.94 to 3036 ± 7.78 mg.L-1) result of a higher final concentration of volatile fatty acids (VFA, 2662.7 mg.L-1). On the other hand, the optimum condition predicted by the statistical model was at 35 °C and 18 g BSG.L-1 (289.1 mL CH4.g-1 TVS), which showed decrease in the organic matter concentration of 78.6% and a lower final concentration of VFA (533.2 mg.L-1). Hydrogenospora and Methanosaeta were identified in this optimum CH4 production condition, where acetoclastic methanogenic pathway prevailed. The CH4 production enhancement was concomitant to acetic acid concentration decrease (from 578.9 to 135.7 mg.L-1).


Asunto(s)
Euryarchaeota , Metano , Anaerobiosis , Reactores Biológicos , Grano Comestible , Ácidos Grasos Volátiles , Metano/análisis , Temperatura
3.
Bioresour Technol ; 330: 124962, 2021 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-33740585

RESUMEN

This study aimed to investigate the effect of bioaugmentation on microbial community and function in a continuous anaerobic process treating lignocellulosic cow manure. One reactor (Rb) received bioaugmentation dosage for a certain period (d100-d170) and stopped afterward (d170-d220), while the same applied to the control (Rc) except sterilized bioaugmentation dosage was introduced. Samples were taken on day130, 170 and 220 from both reactors for metatranscriptomic analysis. The results underlined the promotive effect of bioaugmentation on indigenous microorganisms regarding hydrolysis and methanogenesis. Bioaugmentation contributed to the enrichment of Clostridium, Cellvibrio, Cellulomonas, Bacillus, Fibrobacter, resulting in enhanced cellulase activity (Rb: 0.917-1.081; Rc: 0.551-0.677). Moreover, bioaugmentation brought Rb the prosperity of uncultured_ Bathyarchaeia, a prominent archaeal group responsible for the improved methyl-coenzyme M reductase activity, thus accelerated methanogenesis. Unique metabolic pathways (autotrophic carbon fixation and methanogenesis) in uncultured_ Bathyarchaeia broadened the horizon of its fundamental role as acetogens and methanogens in anaerobic digestion.


Asunto(s)
Euryarchaeota , Estiércol , Anaerobiosis , Animales , Biocombustibles , Reactores Biológicos , Bovinos , Femenino , Metano
4.
J Environ Manage ; 286: 112229, 2021 May 15.
Artículo en Inglés | MEDLINE | ID: mdl-33667821

RESUMEN

Up-flow anaerobic bioreactors are widely applied for high-rate digestion of industrial wastewaters and rely on formation, and retention, of methanogenic granules, comprising of dense, fast-settling, microbial aggregates (approx. 0.5-4.0 mm in diameter). Granule formation (granulation) mechanisms have been reasonably well hypothesized and documented. However, this study used laboratory-scale bioreactors, inoculated with size-separated granular sludge to follow new granule formation, maturation, disintegration and re-formation. Temporal size profiles, volatile solids content, settling velocity, and ultrastructure of granules were determined from each of four bioreactors inoculated only with small granules, four with only large granules, and four with a full complement of naturally-size-distributed granules. Constrained granule size profiles shifted toward the natural distribution, which was associated with maximal bioreactor performance. Distinct morphological features characterized different granule sizes and biofilm development stages, including 'young', 'juvenile', 'mature' and 'old'. The findings offer opportunities toward optimizing management of high-rate, anaerobic digesters by shedding light on the rates of granule growth, the role of flocculent sludge in granulation and how shifting size distributions should be considered when setting upflow velocities.


Asunto(s)
Euryarchaeota , Eliminación de Residuos Líquidos , Anaerobiosis , Reactores Biológicos , Crecimiento y Desarrollo , Aguas del Alcantarillado
5.
Waste Manag ; 124: 26-35, 2021 Apr 01.
Artículo en Inglés | MEDLINE | ID: mdl-33596536

RESUMEN

There have been several reports of landfills exhibiting temperatures as high as 80 to 100 °C. This observation has motivated researchers to understand the causes of the elevated temperatures and to develop predictive models of landfill temperature. The objective of this research was to characterize the methanogenic activity of microbial communities that were derived from landfill samples excavated from a section of a landfill exhibiting gas well temperatures above 55 °C. Specific objectives were to: (1) determine the upper temperature limit for methane production; (2) evaluate the kinetics of methane generation when landfill-derived microcosms are incubated above and below their excavation temperature and derive a temperature inhibition function; and (3) evaluate microbial community shifts in response to temperature perturbations. Landfill microcosms were derived from 57 excavated landfill samples and incubated within ±2.5 °C of their excavation temperature between 42.5 °C and 87.5 °C. Results showed an optimum temperature for methane generation of ~57 °C and a 95% reduction in methane yield at ~72 °C. When select cultures were perturbed between 5 °C below and 15 °C above their in-situ temperature, both the rate and maximum methane production decreased as incubation temperature increased. Microbial community characterization using 16S rRNA amplicon sequencing suggests that thermophilic methanogenic activity can be attributed to methanogens of the genus Methanothermobacter. This study demonstrated that from a microbiological standpoint, landfills may maintain active methanogenic processes while experiencing temperatures in the thermophilic regime (<72 °C).


Asunto(s)
Euryarchaeota , Instalaciones de Eliminación de Residuos , Euryarchaeota/genética , Metano , ARN Ribosómico 16S/genética , Temperatura
6.
Microbiome ; 9(1): 20, 2021 01 22.
Artículo en Inglés | MEDLINE | ID: mdl-33482926

RESUMEN

BACKGROUND: Soil methanogens participate in complex interactions, which determine the community structures and functions. Studies continue to seek the coexistence patterns of soil methanogens, influencing factors and the contribution to methane (CH4) production, which are regulated primarily by species interactions, and the functional significance of these interactions. Here, methane emissions were measured in rice paddies across the Asian continent, and the complex interactions involved in coexistence patterns of methanogenic archaeal communities were represented as pairwise links in co-occurrence networks. RESULTS: The network topological properties, which were positively correlated with mean annual temperature, were the most important predictor of CH4 emissions among all the biotic and abiotic factors. The methanogenic groups involved in commonly co-occurring links among the 39 local networks contributed most to CH4 emission (53.3%), much higher than the contribution of methanogenic groups with endemic links (36.8%). The potential keystone taxa, belonging to Methanobacterium, Methanocella, Methanothrix, and Methanosarcina, possessed high linkages with the methane generation functional genes mcrA, fwdB, mtbA, and mtbC. Moreover, the commonly coexisting taxa showed a very different assembly pattern, with ~ 30% determinism and ~ 70% stochasticity. In contrast, a higher proportion of stochasticity (93~99%) characterized the assembly of endemically coexisting taxa. CONCLUSIONS: These results suggest that the coexistence patterns of microbes are closely tied to their functional significance, and the potential importance of common coexistence further imply that complex networks of interactions may contribute more than species diversity to soil functions. Video abstract.


Asunto(s)
Euryarchaeota/metabolismo , Metano/biosíntesis , Oryza/microbiología , Microbiología del Suelo , Asia , Methanobacterium/metabolismo
7.
Nucleic Acids Res ; 49(3): 1662-1687, 2021 02 22.
Artículo en Inglés | MEDLINE | ID: mdl-33434266

RESUMEN

Ribosomes are intricate molecular machines ensuring proper protein synthesis in every cell. Ribosome biogenesis is a complex process which has been intensively analyzed in bacteria and eukaryotes. In contrast, our understanding of the in vivo archaeal ribosome biogenesis pathway remains less characterized. Here, we have analyzed the in vivo role of the almost universally conserved ribosomal RNA dimethyltransferase KsgA/Dim1 homolog in archaea. Our study reveals that KsgA/Dim1-dependent 16S rRNA dimethylation is dispensable for the cellular growth of phylogenetically distant archaea. However, proteomics and functional analyses suggest that archaeal KsgA/Dim1 and its rRNA modification activity (i) influence the expression of a subset of proteins and (ii) contribute to archaeal cellular fitness and adaptation. In addition, our study reveals an unexpected KsgA/Dim1-dependent variability of rRNA modifications within the archaeal phylum. Combining structure-based functional studies across evolutionary divergent organisms, we provide evidence on how rRNA structure sequence variability (re-)shapes the KsgA/Dim1-dependent rRNA modification status. Finally, our results suggest an uncoupling between the KsgA/Dim1-dependent rRNA modification completion and its release from the nascent small ribosomal subunit. Collectively, our study provides additional understandings into principles of molecular functional adaptation, and further evolutionary and mechanistic insights into an almost universally conserved step of ribosome synthesis.


Asunto(s)
Archaea/enzimología , Metiltransferasas/metabolismo , ARN de Archaea/metabolismo , ARN Ribosómico/metabolismo , Archaea/genética , Movimiento Celular , Crenarchaeota/enzimología , Euryarchaeota/enzimología , Haloferax volcanii/enzimología , Metiltransferasas/fisiología , Biosíntesis de Proteínas , ARN de Archaea/química , ARN Ribosómico/química , Subunidades Ribosómicas Pequeñas de Archaea/enzimología
8.
Mol Cell ; 81(3): 459-472.e10, 2021 02 04.
Artículo en Inglés | MEDLINE | ID: mdl-33382984

RESUMEN

Hi-C has become a routine method for probing the 3D organization of genomes. However, when applied to prokaryotes and archaea, the current protocols are expensive and limited in their resolution. We develop a cost-effective Hi-C protocol to explore chromosome conformations of these two kingdoms at the gene or operon level. We first validate it on E. coli and V. cholera, generating sub-kilobase-resolution contact maps, and then apply it to the euryarchaeota H. volcanii, Hbt. salinarum, and T. kodakaraensis. With a resolution of up to 1 kb, we explore the diversity of chromosome folding in this phylum. In contrast to crenarchaeota, these euryarchaeota lack (active/inactive) compartment-like structures. Instead, their genomes are composed of self-interacting domains and chromatin loops. In H. volcanii, these structures are regulated by transcription and the archaeal structural maintenance of chromosomes (SMC) protein, further supporting the ubiquitous role of these processes in shaping the higher-order organization of genomes.


Asunto(s)
Compartimento Celular , Cromatina/genética , Cromosomas de Archaea , ADN de Archaea/genética , Euryarchaeota/genética , Genoma Arqueal , Transcripción Genética , Ensamble y Desensamble de Cromatina , Regulación de la Expresión Génica Arqueal , Halobacterium salinarum/genética , Haloferax volcanii/genética , Motivos de Nucleótidos , Filogenia , Thermococcus/genética
9.
Nat Commun ; 11(1): 5490, 2020 10 30.
Artículo en Inglés | MEDLINE | ID: mdl-33127909

RESUMEN

Halobacteria (henceforth: Haloarchaea) are predominantly aerobic halophiles that are thought to have evolved from anaerobic methanogens. This remarkable transformation most likely involved an extensive influx of bacterial genes. Whether it entailed a single massive transfer event or a gradual stream of transfers remains a matter of debate. To address this, genomes that descend from methanogen-to-halophile intermediates are necessary. Here, we present five such near-complete genomes of Marine Group IV archaea (Hikarchaeia), the closest known relatives of Haloarchaea. Their inclusion in gene tree-aware ancestral reconstructions reveals an intermediate stage that had already lost a large number of genes, including nearly all of those involved in methanogenesis and the Wood-Ljungdahl pathway. In contrast, the last Haloarchaea common ancestor gained a large number of genes and expanded its aerobic respiration and salt/UV resistance gene repertoire. Our results suggest that complex and gradual patterns of gain and loss shaped the methanogen-to-halophile transition.


Asunto(s)
Archaea/clasificación , Archaea/genética , Euryarchaeota/genética , Genoma Arqueal , Filogenia , Archaea/metabolismo , Proteínas Arqueales/metabolismo , Euryarchaeota/clasificación , Euryarchaeota/metabolismo , Evolución Molecular , Transferencia de Gen Horizontal , Genes Bacterianos , Metagenómica , Metano/metabolismo , Familia de Multigenes , ARN Ribosómico 16S/genética
10.
Bioresour Technol ; 318: 124098, 2020 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-32947139

RESUMEN

Hydrogenotrophic biomethanation in a biotrickling filter has been reported to be a proven technology for biological biogas upgrading in recent studies. However, the preparation of enriched hydrogenotrophic methanogens in a separate reactor prior to biomethanation in a trickled bed is a lengthy procedure and therefore hard to apply on an industrial scale. This study explored the direct inoculation of anaerobic biogas digestate for simultaneous enrichment of hydrogenotrophic methanogens and biofilm immobilisation in a trickled bed system. The direct inoculation and formation of hydrogenotrophic biofilm was successful and resulted in a stable H2 loading rate of 11  [Formula: see text] , with the highest specific methane productivity recorded at 3.03 Nm3mR-3d-1 and a purity of 98% CH4 in thermophilic conditions. The DNA analysis confirmed that hydrogenotrophic methanogens dominated the archaeal consortia.


Asunto(s)
Euryarchaeota , Metano , Anaerobiosis , Biocombustibles , Reactores Biológicos , Hidrógeno
11.
Bioresour Technol ; 316: 123909, 2020 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-32739582

RESUMEN

In this study, temporal impacts of thermal, alkaline/acid and thermal-alkaline sludge pre-treatments on digestion performance and microbiome were investigated and compared in methanogenic sludge digesters. Results showed that thermal and alkaline/acid pre-treatments were efficient in releasing intracellular and EPS organic matter, respectively. The thermal-alkaline pre-treatment showed synergistic impacts of both thermal and alkaline/acid pre-treatments by releasing the major portion of sludge organic matter from solid- to liquid-phase, which result in 60-65% organic carbon removal in subsequent sludge digestion and further optimizing digestion temperature had negligible improvement. The 16S rRNA gene-based analyses suggested that organic matter released from sludge pre-treatments is a major deterministic parameter in shaping sludge microbiome. Pre-treatment specific lineages were identified in different sludge digesters, whereas several taxa were identified as common functionally active populations in sludge digestion. This study provided mechanistic insights into impacts of pre-treatments on digestion performance and microbiome in methanogenic sludge digesters.


Asunto(s)
Euryarchaeota , Microbiota , Anaerobiosis , Reactores Biológicos , Metano , ARN Ribosómico 16S/genética , Aguas del Alcantarillado , Eliminación de Residuos Líquidos
12.
Bioresour Technol ; 316: 123904, 2020 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-32736181

RESUMEN

Red mud-based inorganic polymer spheres were used as alternative pH regulators and process enhancers in sequencing batch anaerobic reactors treating cheese whey. This byproduct tends to quickly acidify under anaerobic conditions, and the common route to control pH and ensure suitable conditions for methane production involves the use of commercial alkaline raw materials. The spheres were synthesized using significant amounts of hazardous and toxic waste, red mud (50 wt% of solid components), whose recycling is challenging. The inorganic polymeric spheres, when compared to virgin alkaline raw materials, improved organic matter removal by 44%, prevented VFA accumulation (acidification degree less than 20%), maintained pH values in a range (6.5-7.2) to ensure maximum methanogenic activity by archaea microorganisms, and boosted the methane volume by ~90%. These promising results demonstrate the feasibility and performance advantages of using these innovative spheres instead of virgin raw materials, which is an important tool towards sustainable development.


Asunto(s)
Euryarchaeota , Polímeros , Anaerobiosis , Reactores Biológicos , Metano , Suero Lácteo
13.
J Environ Manage ; 270: 110937, 2020 Sep 15.
Artículo en Inglés | MEDLINE | ID: mdl-32721355

RESUMEN

Anaerobic-digestion-based technology is key to achieving sustainable water management and resource recovery. It is essential to understand the material flux and kinetics involved in methanogenesis to optimize the organic matter removal and methane production. In this sense, specific methanogenic activity is a cost-effective tool to characterize the biological activity of anaerobic biosludge, to monitor the performance of reactors, and study the kinetics of acetate and H2 conversion to methane. Established protocols are applied for the acetoclastic activity test. However, hydrogenotrophic activity assay remains less widespread and is not standardized. In this work, the assay design for hydrogenotrophic activity is discussed and full calculation is presented, based on the kinetics for the H2/CO2 conversion to methane. An equation to calculate the inoculum size is proposed, suitable for a wide variety of types of biosludge: from a wastewater treatment plant to solid digesters, from a high-rate reactor to lagoons. The applied zero-order model fitted adequately to data for pilot-scale and full-scale anaerobic reactors: the p-values from the ANOVA F-test were below 1E-03; standard deviations for triplicate experiments were between 3 and 12%, coherent with the values found in the literature. Microbial growth during the test was negligible, below 1.2% of the biomass dosed in the vial. As a complement, acetoclastic activity was determined for each sample. The use of both acetoclastic and hydrogenotrophic activity is relevant for the study of the methanogenesis and gives a better characterization of the performance of the biosludge in anaerobic reactors rather than only using the specific acetoclastic methanogenic activity.


Asunto(s)
Reactores Biológicos , Euryarchaeota , Anaerobiosis , Cinética , Metano
14.
Bioresour Technol ; 313: 123702, 2020 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-32615503

RESUMEN

Aiming at relieving acid accumulation in anaerobic digestion (AD), syntrophic associations of syntrophic fatty acid-oxidation bacteria and H2/formate-scavenging methanogens were enriched by feeding propionate, butyrate and formate in an up-flow anaerobic sludge blanket (UASB) reactor. Results showed that methane yield increased by 50% with increasing formate concentration (0-2000 mg COD/L). In addition, the abundance and quantity of SFOB (Syntrophobacter, Smithella and Syntrophomonas) and H2/formate-scavenging methanogens (Methanobacteriales and Methanomicrobiales) were increased after microbial acclimation. The enriched syntrophic associations showed higher propionate and butyrate removal efficiencies of 98.48 ± 1.14% and 99.71 ± 0.71%, respectively. Furthermore, encoding genes of formate dehydrogenase and hydrogenases presented higher abundances after microbial enrichment, which suggested that the enhancements of interspecies formate transfer and interspecies hydrogen transfer between syntrophic associations benefited volatile fatty acids (VFAs) conversion. This research provided an effective strategy to relieve acid accumulation.


Asunto(s)
Euryarchaeota , Anaerobiosis , Bacterias , Bacterias Anaerobias , Reactores Biológicos , Formiatos , Metano
15.
Environ Sci Technol ; 54(14): 8949-8957, 2020 07 21.
Artículo en Inglés | MEDLINE | ID: mdl-32544322

RESUMEN

BES biogas upgrading studies have typically used bicarbonate or commercial gas mixtures as a biocathode substrate instead of anaerobic digester biogas. Therefore, the objective of this study was to (i) compare the performance of a methanogenic BES between CO2-fed and biogas-fed cycles; (ii) investigate possible factors that may account for observed performance differences; and (iii) assess the performance of a biogas-fed biocathode at various applied cathode potentials. The maximum 1-d CH4 production rate in a biogas-fed biocathode (3003 mmol/m2-d) was 350% higher than in a CO2-fed biocathode (666 mmol/m2-d), and the biogas-fed biocathode was capable of maintaining high performance despite a variable biogas feed composition. Anode oxidation of reduced gases (e.g., CH4 and H2S) from biogas may theoretically contribute 4% to 35% of the total charge transfer from anode to cathode at applied cathode potentials of -0.80 to -0.55 V (vs SHE). The introduction of biogas did not significantly change the biocathode archaeal community (dominated by a Methanobrevibacter sp. phylotype), but the bacterial community shifted away from Bacteroidetes and toward Proteobacteria, which may have contributed to the improved performance of the biogas-fed system. This study shows that anaerobic digester biogas is a promising biocathode feedstock for BES biogas upgrading.


Asunto(s)
Biocombustibles , Euryarchaeota , Anaerobiosis , Reactores Biológicos , Dióxido de Carbono , Metano
16.
Extremophiles ; 24(4): 657-672, 2020 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-32533307

RESUMEN

Cultivation and molecular approaches were used to study methanogenesis in saline aquatic system of the Lake Elton (southern Russia), the largest hypersaline lake in Europe. The potential rates of hydrogenotrophic, acetoclastic, methylotrophic and methyl-reducing methanogenesis and diversity of the growth-enriched for by adding electron donors methanogenic communities were studied in the sediment slurry incubations at salinity range from 7 to 275 g/L. The most active pathway detected at all salinities was methylotrophic with a dominance of Methanohalobium and Methanohalophilus genera, at salt saturation and moderately halophilic Methanolobus and Methanococcoides at lower salinity. The absence of methane production from acetate, formate and H2/CO2 under hypersaline conditions was most probably associated with the energy constraints. The contribution of hydrogenotrophic, acetoclastic, and methyl-reducing methanogens to the community increases with a decrease in salinity. Temperature might play an important regulatory function in hypersaline habitats; i.e. methylotrophic methanogens and hydrogenotrophic sulfate-reducing bacteria (SRB) outcompeting methyl-reducing methanogens under mesophilic conditions, and vice versa under thermophilic conditions. An active methane production together with negligible methane oxidation makes hypersaline environments a potential source of methane emission.


Asunto(s)
Euryarchaeota , Lagos , Metano , Methanosarcinaceae , Filogenia , Federación de Rusia
17.
Water Res ; 179: 115883, 2020 Jul 15.
Artículo en Inglés | MEDLINE | ID: mdl-32402863

RESUMEN

Acidic failure is relatively common in anaerobic digesters that receive readily biodegradable food wastes at high loading. Under low pH conditions, the activity of methanogenic biomass decreases resulting in complete failure of the digestion process. In this experimental study, we demonstrated that one of the causes for the digester failure under low pH conditions is due to accelerated decay of methanogenic biomass. When enriched acetate degrading methanogens were exposed to a low pH environment (pH = 5.1 with phosphoric acid) in a batch experiment without external substrate, the specific decay rate was observed to increase as much as 10 times of that at pH 7.0. The specific decay rate for formate degrader was also found to increase under low pH conditions whilst the fermentative microorganisms in the cultures appeared to be tolerant to low pH conditions. A Propidium Mono-Azide-quantitative Polymerase Chain Reaction (PMA-qPCR) analysis revealed that the archaeal biomass dominated by methanogens dropped by 71-79% from the initial concentration after 6 days of the acidic batch experiment whilst the bacterial biomass dominating acidogens decreased by only 25%. The decrease in the number of living cells in the batch experiments at different pH was monitored with time to determine a correlation between decay rate and incubation pH.


Asunto(s)
Euryarchaeota , Anaerobiosis , Archaea , Biomasa , Reactores Biológicos , Concentración de Iones de Hidrógeno , Metano
18.
PLoS One ; 15(4): e0231238, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-32267873

RESUMEN

Members of the phylum Bathyarchaeota and the class Thermoplasmata are widespread in marine and freshwater sediments where they have been recognized as key players in the carbon cycle. Here, we tested the responsiveness of archaeal communities on settled plant debris and sediment from a karstic lake to different organic carbon amendments (amino acids, plant-derived carbohydrates, and aromatics) using a lab-scale microcosm. Changes in the composition and abundance of sediment and biofilm archaeal communities in both DNA and RNA fractions were assessed by 16S rRNA gene amplicon sequencing and qPCR, respectively, after 7 and 30 days of incubation. Archaeal communities showed compositional changes in terms of alpha and beta diversity in relation to the type of carbon source (amino acids vs. plant-derived compounds), the nucleic acid fraction (DNA vs. RNA), and the incubation time (7 vs. 30 days). Distinct groups within the Bathyarchaeota (Bathy-15 and Bathy-6) and the Thermoplasmata (MBG-D) differently reacted to carbon supplements as deduced from the analysis of RNA libraries. Whereas Bathyarchaeota in biofilms showed a long-term positive response to humic acids, their counterparts in the sediment were mainly stimulated by the addition of tryptophan, suggesting the presence of different subpopulations in both habitats. Overall, our work presents an in vitro assessment of the versatility of archaea inhabiting freshwater sediments towards organic carbon and introduces settled leaf litter as a new habitat for the Bathyarchaeota and the Thermoplasmata.


Asunto(s)
Ciclo del Carbono/fisiología , Crenarchaeota/genética , Crenarchaeota/metabolismo , Euryarchaeota/genética , Euryarchaeota/metabolismo , Sedimentos Geológicos , Lagos , Biodiversidad , Biopelículas , Carbono/metabolismo , ADN de Archaea/genética , Ecosistema , Sustancias Húmicas , Filogenia , ARN Ribosómico 16S/genética , Análisis de Secuencia de ADN , Triptófano
19.
Ecotoxicol Environ Saf ; 195: 110481, 2020 Jun 01.
Artículo en Inglés | MEDLINE | ID: mdl-32203775

RESUMEN

Archaea remain important players in global biogeochemical cycles worldwide, including in the highly productive mangrove estuarine ecosystems. In the present study, we have explored the diversity, distribution, and function of the metabolically active fraction of the resident archaeal community of the Sundarban mangrove ecosystem, using both culture-independent and culture-dependent approaches. To evaluate the diversity and distribution pattern of the active archaeal communities, RNA based analysis of the 16S rRNA gene was performed on an Illumina platform. The active Crenarchaeal community was observed to remain constant while active Euryarchaeal community underwent considerable change across the sampling sites depending on varying anthropogenic factors. Haloarchaea were the predominant group in hydrocarbon polluted sediments, leading us to successfully isolate eleven p-hydroxybenzoic acid degrading haloarchaeal species. The isolates could also survive in benzoic acid, naphthalene, and o-phthalate. Quantitative estimation of p-hydroxybenzoic acid degradation was studied on select isolates, and their ability to reduce COD of polluted saline waters of Sundarban was also evaluated. To our knowledge, this is the first ever study combining culture-independent (Next Generation sequencing and metatranscriptome) and culture-dependent analyses for an assessment of archaeal function in the sediment of Sundarban.


Asunto(s)
Archaea/metabolismo , Sedimentos Geológicos/microbiología , Hidrocarburos/metabolismo , Contaminantes Químicos del Agua/metabolismo , Archaea/genética , Archaea/aislamiento & purificación , Biodegradación Ambiental , Crenarchaeota/aislamiento & purificación , Euryarchaeota/aislamiento & purificación , Parabenos/metabolismo , ARN Ribosómico 16S/genética , Humedales
20.
J Environ Manage ; 264: 110421, 2020 Jun 15.
Artículo en Inglés | MEDLINE | ID: mdl-32217313

RESUMEN

Paddy fields are major sources of atmospheric methane (CH4). However, CH4 emissions from cold-waterlogged paddy fields, a major type of paddy soil in China, remain unclear. Here we investigated the CH4 emissions and associated influential factors in cold-waterlogged paddy fields at two sites (Yangxin County and Daye City) in Hubei Province, South China. Normal paddy fields matched with parental material and cropping system were used as the controls. The CH4 emissions from cold-waterlogged fields were significantly higher than those from normal fields with (3.0-4.4-fold) or without (3.5-8.6-fold) rice. Rice planting increased CH4 emissions by 59-78% in cold-waterlogged fields and by 85-247% in normal fields. CH4 instantaneous fluxes were positively correlated with soil temperature and methanogen mcrA (methyl coenzyme M reductase alpha subunit) and methanotroph pmoA (methane monooxygenase) copy numbers at the annual scale. Under rice planting, mcrA copy number was higher in cold-waterlogged fields than in normal fields at both sites, whereas pmoA copy number had the same trend at the Daye site only. Soil temperature and water content influenced mcrA and pmoA copy numbers in the normal paddy fields, whereas soil organic matter content was more influential in the cold-waterlogged paddy fields. These findings suggest that perennial waterlogging is a prerequisite for substantial CH4 emissions from cold-waterlogged paddy fields, and it promotes the proliferation of methanogens and methanotrophs under rice planting. Therefore, CH4 production-oxidation processes are more active in cold-waterlogged paddy fields than in normal paddy fields.


Asunto(s)
Euryarchaeota , Oryza , China , Metano , Suelo , Temperatura
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