RESUMEN
The Dallol geothermal area in the northern part of the Danakil Depression (up to 124-155 meter below sea level) is deemed one of the most extreme environments on Earth. The area is notable for being part of the Afar Depression, an incipient seafloor-spreading center located at the triple junction, between Nubian, Somali and Arabian plates, and for hosting environments at the very edge of natural physical-chemical extremities. The northern part of the Danakil Depression is dominated by the Assale salt plain (an accumulation of marine evaporite deposits) and hosts the Dallol volcano. Here, the interaction between the evaporitic deposit and the volcanisms have created the unique Dallol hot springs, which are highly acidic (pH ~ 0) and saline (saturation) with maximum temperatures ranging between 90 and 109 °C. Here we report for the first time evidence of life existing with these hot springs using a combination of morphological and molecular analyses. Ultra-small structures are shown to be entombed within mineral deposits, which are identified as members of the Order Nanohaloarchaea. The results from this study suggest the microorganisms can survive, and potential live, within this extreme environment, which has implications for understanding the limits of habitability on Earth and on (early) Mars.
Asunto(s)
Euryarchaeota/aislamiento & purificación , Extremófilos/aislamiento & purificación , Sedimentos Geológicos/microbiología , Manantiales de Aguas Termales/microbiología , Microbiota/genética , ADN de Archaea/genética , ADN de Archaea/aislamiento & purificación , Etiopía , Euryarchaeota/genética , Euryarchaeota/ultraestructura , Extremófilos/genética , Extremófilos/ultraestructura , Genes Arqueales/genética , Sedimentos Geológicos/química , Manantiales de Aguas Termales/química , Concentración de Iones de Hidrógeno , Microscopía Electrónica de Transmisión , Filogenia , ARN Ribosómico 16S/genética , SalinidadRESUMEN
Halovirus is a major force that affects the evolution of extreme halophiles and the biogeochemistry of hypersaline environments. However, until now, the systematic studies on the halovirus ecology and the effects of salt concentration on virus-host systems are lacking. To provide more valuable information for understanding ecological strategies of a virus-host system in the hypersaline ecosystem, we studied the interaction between halovirus SNJ1 and its host Natrinema sp.J7-2 under various NaCl concentrations. We found that the adsorption rate and lytic rate increased with salt concentration, demonstrating that a higher salt concentration promoted viral adsorption and proliferation. Contrary to the lytic rate, the lysogenic rate decreased as the salt concentration increased. Our results also demonstrated that cells incubated at a high salt concentration prior to infection increased the ability of the virus to adsorb and lyse its host cells; therefore, the physiological status of host cells also affected the virus-host interaction. In conclusion, SNJ1 acted as a predator, lysing host cells and releasing progeny viruses in hypersaline environments; in low salt environments, viruses lysogenized host cells to escape the damage from low salinity.
Asunto(s)
ADN Viral/genética , Euryarchaeota/efectos de los fármacos , Interacciones Huésped-Patógeno/efectos de los fármacos , Cloruro de Sodio/farmacología , Virus no Clasificados/efectos de los fármacos , Replicación del ADN/efectos de los fármacos , ADN Viral/metabolismo , Ecosistema , Euryarchaeota/ultraestructura , Euryarchaeota/virología , Lisogenia/efectos de los fármacos , Salinidad , Virus no Clasificados/crecimiento & desarrollo , Virus no Clasificados/patogenicidadRESUMEN
The cohort of the ammonia-oxidizing archaea (AOA) of the phylum Thaumarchaeota is a diverse, widespread and functionally important group of microorganisms in many ecosystems. However, our understanding of their biology is still very rudimentary in part because all available genome sequences of this phylum are from members of the Nitrosopumilus cluster. Here we report on the complete genome sequence of Candidatus Nitrososphaera gargensis obtained from an enrichment culture, representing a different evolutionary lineage of AOA frequently found in high numbers in many terrestrial environments. With its 2.83 Mb the genome is much larger than that of other AOA. The presence of a high number of (active) IS elements/transposases, genomic islands, gene duplications and a complete CRISPR/Cas defence system testifies to its dynamic evolution consistent with low degree of synteny with other thaumarchaeal genomes. As expected, the repertoire of conserved enzymes proposed to be required for archaeal ammonia oxidation is encoded by N. gargensis, but it can also use urea and possibly cyanate as alternative ammonia sources. Furthermore, its carbon metabolism is more flexible at the central pyruvate switch point, encompasses the ability to take up small organic compounds and might even include an oxidative pentose phosphate pathway. Furthermore, we show that thaumarchaeota produce cofactor F420 as well as polyhydroxyalkanoates. Lateral gene transfer from bacteria and euryarchaeota has contributed to the metabolic versatility of N. gargensis. This organisms is well adapted to its niche in a heavy metal-containing thermal spring by encoding a multitude of heavy metal resistance genes, chaperones and mannosylglycerate as compatible solute and has the genetic ability to respond to environmental changes by signal transduction via a large number of two-component systems, by chemotaxis and flagella-mediated motility and possibly even by gas vacuole formation. These findings extend our understanding of thaumarchaeal evolution and physiology and offer many testable hypotheses for future experimental research on these nitrifiers.
Asunto(s)
Amoníaco/metabolismo , Euryarchaeota/genética , Euryarchaeota/metabolismo , Genoma Bacteriano , Adaptación Biológica/fisiología , Evolución Biológica , Transporte Biológico , Carbono/metabolismo , Quimiotaxis/fisiología , Ecosistema , Metabolismo Energético/fisiología , Euryarchaeota/ultraestructura , Metales Pesados/toxicidad , Oxidación-Reducción , FilogeniaRESUMEN
Terry Beveridge's enthusiasm about the ingenuity of microorganisms has stimulated many new avenues of microbial research. One example where Terry's observations helped direct the scientific process was in the analysis of the draft genome of the thermoacidophilic archaeum, Aciduliprofundum boonei. This deep-sea vent heterotroph ferments peptides as its primary metabolic pathway, using numerous enzymes encoding for proteolytic or peptidolytic activities. An almost complete modified Embden-Meyerhof-Parnas pathway operates in the gluconeogenic direction. Terry was particularly intrigued by the S-layer and flagellum of A. boonei. Although only putative genes for the S-layer protein could be identified, several genes encoding for glycosyl transferases were located in the draft genome that could glycosylate the S-layer proteins and protect the proteins from the acidic environment. Furthermore, A. boonei possesses a unique organization to its flagellum genes and may represent a third organizational type within the Archaea.
Asunto(s)
Euryarchaeota/enzimología , Euryarchaeota/ultraestructura , Flagelos/genética , Genómica/métodos , Glicosiltransferasas/genética , Modelos Biológicos , Flagelos/ultraestructura , Componentes del Gen , Microscopía Electrónica , Familia de MultigenesRESUMEN
Recently it was shown that Pyrococcus furiosus uses its flagella not only for swimming, but also for establishment of cell-cell connections, and for adhesion to abiotic surfaces. Therefore, it was asked here if P. furiosus might be able to adhere also to biotic surfaces. Since Methanopyrus kandleri can be found in habitats similar to those of P. furiosus (seawater close to the boiling point and anaerobic conditions) it was tested if interactions between both archaea occur. Using a standard medium and a gas phase reduced in H2 (compared with the optimal gas phase for M. kandleri) we were able to grow both species in a stable coculture. Very interestingly, M. kandleri could adhere to glass under such conditions, but not P. furiosus. This latter archaeum, however, was able to adhere onto M. kandleri cells and onto itself, resulting in structured biofilms on glass. These very often appeared as a bottom layer of M. kandleri cells covered by a multitude of P. furiosus cells. Interactions between P. furiosus and M. kandleri were mediated not only by flagella, but also by direct cell-cell contact.
Asunto(s)
Biopelículas , Euryarchaeota/crecimiento & desarrollo , Pyrococcus furiosus/crecimiento & desarrollo , Adhesión Celular , Técnicas de Cocultivo , Euryarchaeota/ultraestructura , Flagelos/fisiología , Microscopía Confocal , Microscopía Electrónica de Rastreo , Microscopía Electrónica de Transmisión , Pyrococcus furiosus/ultraestructuraRESUMEN
An extremely acidic (pH 2.5-2.75) metal-rich stream draining an abandoned mine in the Iberian Pyrite Belt, Spain, was ramified with stratified macroscopic gelatinous microbial growths ('acid streamers' or 'mats'). Microbial communities of streamer/mat growths sampled at different depths, as well as those present in the stream water itself, were analysed using a combined biomolecular and cultivation-based approach. The oxygen-depleted mine water was dominated by the chemolithotrophic facultative anaerobe Acidithiobacillus ferrooxidans, while the streamer communities were found to be highly heterogeneous and very different to superficially similar growths reported in other extremely acidic environments. Microalgae accounted for a significant proportion of surface streamer biomass, while subsurface layers were dominated by heterotrophic acidophilic bacteria (Acidobacteriacae and Acidiphilium spp.). Sulfidogenic bacteria were isolated from the lowest depth streamer growths, where there was also evidence for selective biomineralization of copper sulfide. Archaeal clones (exclusively Euryarchaeota) were recovered from streamer samples, as well as the mine stream water. Both sunlight and reduced inorganic chemicals (predominantly ferrous iron) served as energy sources for primary producers in this ecosystem, promoting complex microbial interactions involving transfer of electron donors and acceptors and of organic carbon, between microorganisms in the stream water and the gelatinous streamer growths. Microbial transformations were shown to impact the biogeochemical cycling of iron and sulfur in the acidic stream, severely restricting the net oxidation of ferrous iron even when the initially anoxic waters were oxygenated by indigenous acidophilic algae. A model accounting for the biogeochemistry of iron and sulfur in the mine waters is described, and the significance of the acidophilic communities in regulating the geochemistry of acidic, metal-rich waters is described.
Asunto(s)
Acidiphilium/genética , Acidithiobacillus/genética , Ecosistema , Eucariontes/genética , Euryarchaeota/genética , Ríos/microbiología , Microbiología del Agua , Acidiphilium/ultraestructura , Acidithiobacillus/ultraestructura , Secuencia de Bases , Cartilla de ADN/genética , Eucariontes/ultraestructura , Euryarchaeota/ultraestructura , Concentración de Iones de Hidrógeno , Microscopía Electrónica de Rastreo , Minería , Modelos Biológicos , Datos de Secuencia Molecular , Filogenia , Polimorfismo de Longitud del Fragmento de Restricción , ARN Ribosómico 18S/genética , Ríos/química , Análisis de Secuencia de ADN , España , SulfurosRESUMEN
Novel, low-abundance microbial species can be easily overlooked in standard polymerase chain reaction (PCR)-based surveys. We used community genomic data obtained without PCR or cultivation to reconstruct DNA fragments bearing unusual 16S ribosomal RNA (rRNA) and protein-coding genes from organisms belonging to novel archaeal lineages. The organisms are minor components of all biofilms growing in pH 0.5 to 1.5 solutions within the Richmond Mine, California. Probes specific for 16S rRNA showed that the fraction less than 0.45 micrometers in diameter is dominated by these organisms. Transmission electron microscope images revealed that the cells are pleomorphic with unusual folded membrane protrusions and have apparent volumes of <0.006 cubic micrometer.
Asunto(s)
Biopelículas , Ecosistema , Euryarchaeota , Genoma Arqueal , Secuencia de Aminoácidos , Secuencia de Bases , California , Membrana Celular/ultraestructura , Elementos Transponibles de ADN , ADN de Archaea , Bases de Datos Genéticas , Euryarchaeota/genética , Euryarchaeota/fisiología , Euryarchaeota/ultraestructura , Genes Arqueales , Genes de ARNr , Concentración de Iones de Hidrógeno , Microscopía Electrónica de Transmisión , Minería , Datos de Secuencia Molecular , Sondas de Oligonucleótidos , Filogenia , Pirofosfatasas/genética , Pirofosfatasas/metabolismo , ARN Ribosómico 16S/genética , TemperaturaRESUMEN
The electron microscopic study of the structure of the motility apparatus of the archaea Halobacterium salinarium 4W12 and Natronobacterium magadii confirmed our earlier observation that the motility apparatus of halobacteria contains an intracellular disk-shaped lamellar structure (DLS). Polar cap structures (PCSs) isolated from the halobacterium were preliminarily identified as the DLSs. The PCSs in complexes with flagella were also isolated from the haloalkaliphilic bacterium N. magadii. The specific structure of the archaeal motility apparatus is discussed.
Asunto(s)
Euryarchaeota/ultraestructura , Flagelos/ultraestructura , Microscopía Electrónica , Especificidad de la EspecieRESUMEN
This paper reports on the adhesion of sulfate-reducing bacteria (SRB) and methanogenic archaea on polyurethane foam (PU), vegetal carbon (VC), low-density polyethylene (PE) and alumina-based ceramics (CE). Anaerobic differential reactors fed with a sulfate-rich synthetic wastewater were used to evaluate the formation of a biofilm. The PU presented the highest specific biomass concentration throughout the experiment, achieving 872 mg TVS/g support, while 84 mg TVS/g support was the maximum value obtained for the other materials. FISH results showed that bacterial cells rather than archaeal cells were predominant on the biofilms. These cells, detected with EUB338 probe, accounted for 76.2% (+/-1.6%), 79.7% (+/-1.3%), 84.4% (+/-1.4%) and 60.2% (+/-1.0%) in PU, VC, PE and CE, respectively, of the 4'6-diamidino-2-phenylindole (DAPI)-stained cells. From these percentages, 44.8% (+/-2.1%), 55.4% (+/-1.2%), 32.7% (+/-1.4%) and 18.1% (+/-1.1%), respectively, represented the SRB group. Archaeal cells, detected with ARC915 probe, accounted for 33.1% (+/-1.6%), 25.4% (+/-1.3%), 22.6% (+/-1.1%) and 41.9% (+/-1.0%) in PU, VC, PE and CE, respectively, of the DAPI-stained cells. Sulfate reduction efficiencies of 39% and 45% and mean chemical oxygen demand (COD) removal efficiencies of 86% and 90% were achieved for PU and VC, respectively. The other two supports, PE and CE, provided mean COD removal efficiencies of 84% and 86%, respectively. However, no sulfate reduction was observed with these supports.
Asunto(s)
Bacterias Anaerobias/crecimiento & desarrollo , Biopelículas/crecimiento & desarrollo , Reactores Biológicos/microbiología , Euryarchaeota/crecimiento & desarrollo , Técnicas Microbiológicas/instrumentación , Óxido de Aluminio , Bacterias Anaerobias/ultraestructura , Adhesión Bacteriana , Biomasa , Carbono , Euryarchaeota/ultraestructura , Hibridación Fluorescente in Situ , Indoles/metabolismo , Microscopía Electrónica de Rastreo , Consumo de Oxígeno , Polietileno , Poliuretanos , Sulfatos/metabolismo , Factores de TiempoRESUMEN
In the surface waters of sulfidic springs near Regensburg, Bavaria, Germany, the SM1 euryarchaeon, together with filamentous bacteria, forms the recently described unique string-of-pearls community. In addition to naturally occurring string-of-pearls communities, the growth of these communities was also observed on polyethylene nets provided as an artificial attachment material in the streamlets of springs. In order to learn more about the distribution and origin of the SM1 euryarchaeon and its possible occurrence in the subsurface, polyethylene nets were incubated as deeply as possible in different spring holes. After a short residence time, slime-like, milky drops, almost completely composed of SM1 euryarchaeon, were attached to the nets, indicating that this organism grows independent of a partner in deeper earth layers. A newly designed in situ biofilm trapping system allowed the quantitative harvesting of organisms exhibiting this newly discovered lifestyle of the SM1 euryarchaeon for detailed biological studies. The discovery of naturally occurring archaeal biofilms extends our knowledge of the biology and ecological significance of archaea in their environments.
Asunto(s)
Biopelículas/crecimiento & desarrollo , Frío , Euryarchaeota/crecimiento & desarrollo , Agua Dulce/microbiología , Electroforesis en Gel de Campo Pulsado , Euryarchaeota/genética , Euryarchaeota/fisiología , Euryarchaeota/ultraestructura , Hibridación Fluorescente in Situ , Microscopía Electrónica , Polietileno , Especificidad de la Especie , SulfurosRESUMEN
This study was performed to optimize both acidogenic hydrogenesis and methanogenesis, and then to develop a pilot-scale two-stage process producing not only CH4 but also H2. Firstly, acidogenic hydrogenesis of food waste was examined in pilot-scale leaching-bed reactors using dilution rate (D) as a tool to improve the environmental conditions. The maximum efficiency of 71.4% was obtained by adjusting D from 4.5 to 2.5 d(-1) depending on the state of degradation. Secondly, the wastewater from acidogenic hydrogenesis was converted to CH4 in a pilot-scale UASB reactor. The COD removal efficiency exceeded 95% up to the loading rates of 13.1 g COD/Ld, which corresponded to HRT of 0.25 d (6 h). Lastly, a pilot-scale two-stage process was devised based on a combination of acidogenic hydrogenesis and methanogenesis. Over 120 days, the pilot-scale process resulted in large VS reduction of 70.9% at the high loading rate of 12.5 kg VS/m3/d in a short SRT of 8 days.
Asunto(s)
Bacterias Anaerobias/metabolismo , Euryarchaeota/metabolismo , Hidrógeno/metabolismo , Metano/metabolismo , Eliminación de Residuos/métodos , Fuentes de Energía Bioeléctrica , Reactores Biológicos/microbiología , Conservación de los Recursos Energéticos , Euryarchaeota/ultraestructura , Ácidos Grasos Volátiles/metabolismo , Residuos de Alimentos , Proyectos Piloto , Aguas del AlcantarilladoRESUMEN
In the purple membrane (PM) of halobacteria, lipids stabilize the trimeric arrangement of bacteriorhodopsin (BR) molecules and mediate the packing of the trimers in a regular crystalline arrangement. To date, the identification and quantification of these lipids has been based either on lipid extraction procedures or structural models. By directly solubilizing PMs from Halobacterium salinarum in aqueous detergent solutions (SDS or Triton X-100), we avoided any separation or modification steps that might modify the lipid composition or even the lipid molecules themselves. Our analysis of integral PM preparations should resolve partially conflicting literature data on the lipid composition of the PM. Using 31P and 1H NMR of detergent-solubilized but otherwise untreated samples, we found two glycolipids and 6.4 +/- 0.1 phospholipids per BR molecule, 4.4 +/- 0.1 of the latter being the phosphatidylglycerophosphate methyl ester. The only glycolipid detected was S-TGD-1. For an additional glycolipid, glycocardiolipin, that was recently identified in lipid extracts, we show that it was produced mainly during the lipid extraction procedure but also was partially dependent on the preparation of the PM suspensions.
Asunto(s)
Euryarchaeota/química , Lípidos/análisis , Resonancia Magnética Nuclear Biomolecular , Membrana Púrpura/química , Detergentes , Euryarchaeota/ultraestructura , Glucolípidos/análisis , Fosfolípidos/análisis , Isótopos de Fósforo , ProtonesRESUMEN
Methanogenic bioreactor communities were used as model ecosystems to evaluate the relationship between functional stability and community structure. Replicated methanogenic bioreactor communities with two different community structures were established. The effect of a substrate loading shock on population dynamics in each microbial community was examined by using morphological analysis, small-subunit (SSU) rRNA oligonucleotide probes, amplified ribosomal DNA (rDNA) restriction analysis (ARDRA), and partial sequencing of SSU rDNA clones. One set of replicated communities, designated the high-spirochete (HS) set, was characterized by good replicability, a high proportion of spiral and short thin rod morphotypes, a dominance of spirochete-related SSU rDNA genes, and a high percentage of Methanosarcina-related SSU rRNA. The second set of communities, designated the low-spirochete (LS) set, was characterized by incomplete replicability, higher morphotype diversity dominated by cocci, a predominance of Streptococcus-related and deeply branching Spirochaetales-related SSU rDNA genes, and a high percentage of Methanosaeta-related SSU rRNA. In the HS communities, glucose perturbation caused a dramatic shift in the relative abundance of fermentative bacteria, with temporary displacement of spirochete-related ribotypes by Eubacterium-related ribotypes, followed by a return to the preperturbation community structure. The LS communities were less perturbed, with Streptococcus-related organisms remaining prevalent after the glucose shock, although changes in the relative abundance of minor members were detected by morphotype analysis. A companion paper demonstrates that the more stable LS communities were less functionally stable than the HS communities (S. A. Hashsham, A. S. Fernandez, S. L. Dollhopf, F. B. Dazzo, R. F. Hickey, J. M. Tiedje, and C. S. Criddle, Appl. Environ. Microbiol. 66:4050-4057, 2000).
Asunto(s)
Reactores Biológicos , Ecosistema , Euryarchaeota/crecimiento & desarrollo , Glucosa/metabolismo , Metano/metabolismo , Anaerobiosis , ADN de Archaea/análisis , ADN de Archaea/genética , ADN Bacteriano/análisis , ADN Bacteriano/genética , ADN Ribosómico/análisis , ADN Ribosómico/genética , Euryarchaeota/clasificación , Euryarchaeota/metabolismo , Euryarchaeota/ultraestructura , Procesamiento de Imagen Asistido por Computador , Methanosarcina/clasificación , Methanosarcina/genética , Methanosarcina/metabolismo , Datos de Secuencia Molecular , Sondas de Oligonucleótidos , ARN Ribosómico/genética , Mapeo Restrictivo , Análisis de Secuencia de ADN , Spirochaetales/clasificación , Spirochaetales/genética , Spirochaetales/metabolismo , Streptococcus/clasificación , Streptococcus/genética , Streptococcus/metabolismoRESUMEN
16S rRNA-targeted in situ hybridization combined with confocal laser scanning microscopy was used to elucidate the spatial distribution of microbes within two types of methanogenic granular sludge, mesophilic (35 degrees C) and thermophilic (55 degrees C), in upflow anaerobic sludge blanket reactors fed with sucrose-, acetate-, and propionate-based artificial wastewater. The spatial organization of the microbes was visualized in thin sections of the granules by using fluorescent oligonucleotide probes specific to several phylogenetic groups of microbes. In situ hybridization with archaeal- and bacterial-domain probes within granule sections clearly showed that both mesophilic and thermophilic granules had layered structures and that the outer layer harbored mainly bacterial cells while the inner layer consisted mainly of archaeal cells. Methanosaeta-, Methanobacterium-, Methanospirillum-, and Methanosarcina-like cells were detected with oligonucleotide probes specific for the different groups of methanogens, and they were found to be localized inside the granules, in both types of which dominant methanogens were members of the genus Methanosaeta. For specific detection of bacteria which were previously detected by whole-microbial-community 16S ribosomal DNA (rDNA)-cloning analysis (Y. Sekiguchi, Y. Kamagata, K. Syutsubo, A. Ohashi, H. Harada, and K. Nakamura, Microbiology 144:2655-2665, 1998) we designed probes specific for clonal 16S rDNAs related to unidentified green nonsulfur bacteria and clones related to Syntrophobacter species. The probe designed for the cluster closely related to Syntrophobacter species hybridized with coccoid cells in the inner layer of the mesophilic granule sections. The probe for the unidentified bacteria which were clustered with the green nonsulfur bacteria detected filamentous cells in the outermost layer of the thermophilic sludge granule sections. These results revealed the spatial organizations of methanogens and uncultivated bacteria and their in situ morphologies and metabolic functions in both mesophilic and thermophilic granular sludges.
Asunto(s)
Bacterias/aislamiento & purificación , Euryarchaeota/aislamiento & purificación , Hibridación Fluorescente in Situ , Aguas del Alcantarillado/microbiología , Anaerobiosis , Archaea/genética , Archaea/aislamiento & purificación , Bacterias/genética , Bacterias/ultraestructura , Reactores Biológicos , Euryarchaeota/genética , Euryarchaeota/ultraestructura , Methanobacteriaceae/genética , Methanobacteriaceae/aislamiento & purificación , Microscopía Confocal , Filogenia , ARN Ribosómico 16S/genética , Administración de Residuos , Microbiología del AguaRESUMEN
Immunoelectron microscopic studies of prokaryotes were performed with anti-actin antibodies directed against the C terminus of actin. Studies on ultrathin sections revealed high proportions of the overall label close to the cell periphery in Escherichia coli, Ralstonia eutropha, Thermoanaerobacterium thermosulfurigenes, T. thermosaccharolyticum, and Methanococcus jannaschii. Substantial label also in the cytoplasm was observed in Bacillus sp., Methanococcus voltae, and Methanobacterium thermoautotrophicum. Only very minor amounts of label were found in the nucleoid region of the cells. Whole-mount immunogold studies, combined with negative staining, revealed the existence of an intracellular network of fibrils which could be labeled by anti-actin antibodies. This network is assumed to be located below the cytoplasmic membrane all around the cytoplasm. It appears to have properties that would allow its function as a cytoskeleton-like structure preserving cell shape.
Asunto(s)
Bacterias/ultraestructura , Citoesqueleto/ultraestructura , Euryarchaeota/ultraestructura , Actinas/análisis , Alcaligenes/ultraestructura , Clostridium/ultraestructura , Escherichia coli/ultraestructura , Methanobacterium/ultraestructura , Methanococcus/ultraestructura , Microscopía Inmunoelectrónica/métodosRESUMEN
A morphologically distinct, filamentous methanogen was isolated from hindguts of the subterranean termite, Reticulitermes flavipes (Kollar) (Rhinotermitidae), wherein it was part of the microbiota colonizing the hindgut wall. Individual filaments of strain RFM-3 were 0.23-0.28 micron in diameter and usually > 50 micron in length and aggregated into flocs that were often >/= 0.1 mm in diameter. Optimal growth of strain RFM-3 was obtained at pH 7.0-7.2 and 30 degrees C with a yeast-extract-supplemented, dithiothreitol-reduced medium in which cells produced stoichiometric amounts of methane from H2 + CO2. The morphology and gram-positive staining reaction of strain RFM-3, as well as its resistance to cell lysis by various chemical agents and its restriction to H2 + CO2 as an energy source, suggested that it was a member of the Methanobacteriaceae. The nucleotide sequence of the SSU-rRNA-encoding gene of strain RFM-3 confirmed this affiliation and also supported its recognition as a new species of Methanobrevibacter, for which the epithet filiformis is herewith proposed. Although M. filiformis was one of the dominant methanogens in R. flavipes collected from Woods Hole (Mass., USA), cells of similar morphology were not consistently observed in R. flavipes collected from different geographical locations.
Asunto(s)
Euryarchaeota/aislamiento & purificación , Insectos/microbiología , Intestinos/microbiología , Methanobacteriaceae/aislamiento & purificación , Animales , Euryarchaeota/genética , Euryarchaeota/ultraestructura , Methanobacteriaceae/genética , Methanobacteriaceae/ultraestructura , Filogenia , ARN de Archaea/análisis , ARN de Archaea/genética , ARN Ribosómico/análisis , ARN Ribosómico/genéticaRESUMEN
Methanogenium frigidum sp. nov. was isolated from the perennially cold, anoxic hypolimnion of Ace Lake in the Vesfold Hills of Antarctica. The cells were psychrophilic, exhibiting most rapid growth at 15 degrees C and no growth at temperatures above 18 to 20 degrees C. The cells were irregular, nonmotile coccoids (diameter, 1.2 to 2.5 microns) that occurred singly and grew by CO2 reduction by using H2 as a reductant. Formate could replace H2, but growth was slower. Acetate, methanol, and trimethylamine were not catabolized. Cells grew with acetate as the only organic compounds in the culture medium, but growth was much faster in medium also supplemented with peptones and yeast extract. The cells were slightly halophilic; good growth occurred in medium supplemented with 350 to 600 mM Na+, but no growth occurred with 100 or 850 mM Na+. The pH range for growth was 6.5 to 7.9; no growth occurred at pH 6.0 or 8.5. Growth was slow (maximum specific growth rate, 0.24 day-1; doubling time, 2.9 days). This is the first report of a psychrophilic methanogen growing by CO2 reduction.
Asunto(s)
Euryarchaeota/clasificación , Euryarchaeota/genética , Filogenia , Regiones Antárticas , Medios de Cultivo , Euryarchaeota/crecimiento & desarrollo , Euryarchaeota/fisiología , Euryarchaeota/ultraestructura , Concentración de Iones de Hidrógeno , Biología Marina , Datos de Secuencia Molecular , Cloruro de Sodio , Temperatura , Microbiología del AguaRESUMEN
The addition of support materials, such as sepiolite, to fluidized-bed anaerobic digesters enhances the methane production by increasing the colonization by syntrophic microbiota. However, the efficiency in the methanogenesis depends on the particle size of the support material, the highest level of methane production being obtained by the smaller particle size sepiolite. Because of the porosity and physico-chemical characteristics of these support materials, the anaerobic microbial consortia formed quickly (after one week of incubation). The predominant methanogenic bacteria present in the active granules, detected both by immunofluorescence using specific antibodies and by scanning electron microscopy, were acetoclastic methanogens, mainly Methanosarcina and Methanosaeta.
Asunto(s)
Euryarchaeota/metabolismo , Silicatos de Magnesio , Metano/metabolismo , Eliminación de Residuos Líquidos/instrumentación , Anaerobiosis , Animales , Euryarchaeota/aislamiento & purificación , Euryarchaeota/ultraestructura , Técnica del Anticuerpo Fluorescente Indirecta , Methanosarcina/aislamiento & purificación , Methanosarcina/metabolismo , Methanosarcina/ultraestructura , Microscopía Electrónica de Rastreo , Tamaño de la Partícula , Ratas , Ratas Wistar , Propiedades de SuperficieRESUMEN
From Methanopyrus kandleri, the most thermophilic methanogen known so far, we have purified to homogeneity a protein complex of high molecular mass. Image analysis of transmission electron micrographs revealed a barrel-shaped particle composed of two rings with 8-fold symmetry. Only one type of subunit could be detected. The corresponding gene has been cloned and sequenced. The deduced amino acid sequence shows high homology with the members of group II chaperonins. The structure of the projection and the sequence homology suggest that this particle is the first thermosome isolated from a methanogen.
Asunto(s)
Chaperoninas/ultraestructura , Euryarchaeota/metabolismo , Euryarchaeota/ultraestructura , Orgánulos/ultraestructura , Secuencia de Aminoácidos , Secuencia de Bases , Chaperoninas/biosíntesis , Chaperoninas/química , Cromatografía en Gel , Clonación Molecular , Cartilla de ADN , Electroforesis en Gel de Poliacrilamida , Euryarchaeota/genética , Genes Bacterianos , Calor , Humanos , Microscopía Electrónica , Datos de Secuencia Molecular , Peso Molecular , Orgánulos/química , Reacción en Cadena de la Polimerasa , Proteínas Recombinantes/biosíntesis , Proteínas Recombinantes/química , Proteínas Recombinantes/ultraestructura , Homología de Secuencia de AminoácidoRESUMEN
Most of the small ciliate protozoa, including Dasytricha ruminantium and Entodinium spp. living in the rumen of sheep, were found to have intracellular bacteria. These bacteria were not present in digestive vacuoles. They showed characteristic coenzyme F420 autofluorescence and they were detected with a rhodamine-labelled Archaea-specific oligonucleotide probe. The measured volume percent of autofluorescing bacteria (1%) was close to the total volume of intracellular bacteria estimated from TEM stereology. Thus it is likely that all of the bacteria living in the cytoplasm of these ciliates were endosymbiotic methanogens, using H2 evolved by the host ciliate to form methane. Intracellular methanogens appear to be much more numerous than those attached to the external cell surface of ciliates.