Bioelectrochemical stimulation of electromethanogenesis at a seawater-based subsurface aquifer in a natural gas field. Energy Res. Detection of coenzyme F in deep sea sediments: a key molecule for biological methanogenesis. We report the presence of coenzyme factor F , a prosthetic group of Me coenzyme M reductase for archaeal methanogenesis, in the deep sub-seafloor biosphere.
At This is about three orders of magnitude lower than typical concns. On the basis of the concn. Quantitative analysis of coenzyme F in environmental samples: a new diagnostic tool for methanogenesis and anaerobic methane oxidation. Coenzyme F is a nickel hydrocorphinoid and is the prosthetic group of methyl-coenzyme M reductase that catalyzes the last step of the methanogenic reaction sequence and its reversed reaction for anaerobic methane oxidn.
As such, function-specific compd. Herein, we report the development of a technique for high-sensitivity anal. The lower detection limit of F anal. F concns.
Estimation of methanogenesis by quantification of coenzyme F in marine sediments. Terra Scientific Publishing Co. Coenzyme F is the hydrocorphinoid nickel complex which acts as active site in methyl-coenzyme M reductase MCR. The MCR-F complex catalyzes the last step of methanogenesis: redn.
Since F is a common enzyme for methanogens, it can be a function-specific biomarker to est. A recently developed high sensitive method for coenzyme F anal. Aggregatilinea lenta gen.
Nakahara, Nozomi; Nobu, Masaru K. Microbiology Society. A novel slow-growing, facultatively anaerobic, filamentous bacterium, strain MO-CFX2T, was isolated from a methanogenic microbial community in a continuous-flow bioreactor that was established from subseafloor sediment collected off the Shimokita Peninsula of Japan.
Cells were multicellular filamentous, non-motile and Gram-stain-neg. Cells possessed pili-like structures on the cell surface and a multilayer structure in the cytoplasm. Growth of the strain was obsd. Under optimum growth conditions, doubling time and max. The major cellular fatty acids were satd. C16 : 0 Based on these phenotypic and genomic properties, we propose the name Aggregatilinea lenta gen.
Microbes Environ. Microbes and environments , 27 4 , ISSN:. Microbial community structures in methane seep sediments in the Nankai Trough were analyzed by tag-sequencing analysis for the small subunit SSU rRNA gene using a newly developed primer set. Diversity and richness were examined by 8, and 7, tag-sequences from sediments at 5 and 25 cm below the seafloor cmbsf , respectively.
The estimated diversity and richness in the methane seep sediment are as high as those in soil and deep-sea hydrothermal environments, although the tag-sequences obtained in this study were not sufficient to show whole microbial diversity in this analysis. Developing ultra small-scale radiocarbon sample measurement at the University of Tokyo. Radiocarbon , 52 , — , [ Crossref ], Google Scholar There is no corresponding record for this reference.
Position-dependent radiocarbon content of the macroalgae Undaria pinnatifida as an indicator of oceanographic conditions during algal growth.
Radiocarbon content of dioxide and methane in hydrothermal fluids of Okinawa Trough vents. Small- to ultra-small-scale radiocarbon measurements using newly installed single-stage AMS at the University of Tokyo.
Methods Phys. Elsevier B. Small- to ultra-small-scale radiocarbon 14C measurements are an essential technique for compd. We improved the pretreatment method to reduce modern and 14C-dead carbon contaminations.
The modern and 14C-dead carbon contaminations from combustion and graphitization were estd. Furthermore, we examd. As a result, we succeeded in conducting small- to ultra-small-scale 14C measurements. This is the first single stage AMS system installed in Japan. The system is equipped with a 40 solid sample ion source MC-SNICS-II , sequential injection system at low energy mass spectrometry side, open air kV high energy deck including helium gas stripper which acts as a mol.
The performance tests with 11 ref. Thus our routine 14C measurements have been started since August and maintaining high performance. We have measured about unknown samples during this period. Determination of iodide in seawater by ion chromatography. A simple and highly sensitive ion chromatog. A high-capacity anion-exchange resin with polystyrene-divinylbenzene matrix was used for preconcn. The detection limit was 0. This method was applied to the detn. The biomass, community structure, and spatial distribution of the sedimentary microbiota from a high-energy area of the deep sea.
Deep-Sea Res. Summary : We carried out a regional survey on the archaea compn. Environmental preferences substantially differed among lineages, with Aenigmarchaeota and Methanomicrobia having the largest habitat breadth, and Thermoplasmata, AOA and Micrarchaeota having the smallest. Pacearchaeota and Woesearchaeota had been mostly reported from saline habitats and sediments, but surface waters of oligotrophic alpine lakes are suitable environments for such ecol. Insights into the ecology, evolution, and metabolism of the widespread Woesearchaeotal lineages.
Microbiome , 6 1 , ISSN:. Phylogenetic analysis shows a high diversity with 26 proposed subgroups for this recently discovered archaeal phylum, which are widely distributed in different biotopes but primarily in inland anoxic environments. Ecological patterns analysis and ancestor state reconstruction for specific subgroups reveal that oxic status of the environments is the key factor driving the distribution and evolutionary diversity of Woesearchaeota. A selective distribution to different biotopes and an adaptive colonization from anoxic to oxic environments can be proposed and supported by evidence of the presence of ferredoxin-dependent pathways in the genomes only from anoxic biotopes but not from oxic biotopes.
Metabolic reconstructions support an anaerobic heterotrophic lifestyle with conspicuous metabolic deficiencies, suggesting the requirement for metabolic complementarity with other microbes. Both lineage abundance distribution and co-occurrence network analyses across diverse biotopes confirmed metabolic complementation and revealed a potential syntrophic relationship between Woesearchaeota and methanogens, which is supported by metabolic modeling.
If correct, Woesearchaeota may impact methanogenesis in inland ecosystems. Microbial community structure and functionality in the deep sea floor: Evaluating the causes of spatial heterogeneity in a submarine canyon system NW Mediterranean, Spain. Iodine and microbial interactions in an organic soil. Iodine in groundwater discharging from a geol. Previous work indicated that satn.
Bog water and peat of an iodine-rich bog were studied to elucidate the role of microorganisms in the retention and accumulation of iodine in a temperate wetland. Agar plat culture of a wide spectrum of microbes, including yeasts and molds, with bog groundwater showed anaerobes to be more sensitive to high iodine concns.
Although iron-related and slime-forming bacteria were not affected at mg I litre-1, iodine was toxic to sulfate-related bacteria SRB , as indicated by Biol. Activity Reaction Tests. Microbe enumeration in iodine-rich bog groundwater, using acridine orange staining, showed that the native wetland microbe population was sensitive to concns. Three independent expts. Iodine sorption to fresh peat was slightly slower and more limited under anoxic conditions.
Autoclaving the peat, reinoculation following autoclaving and a sucrose addn. These results suggest that microbes may only play a minor and indirect role in iodine sorption through the decompn. Effects of microorganisms on the fate of iodine in the soil environment. Microbial contribution to global iodine cycling: volatilization, accumulation, reduction, oxidation, and sorption of iodine.
Microbes and environments , 23 4 , ISSN: Iodine is an essential trace element for humans and animals because of its important role as a constituent of thyroid hormones.
If the anthropogenic iodine I, half-life: 1. Therefore, it is necessary to obtain better information on the behavior of iodine in the environment for accurate safety assessments of I.
Major pathways of iodine cycling are the volatilization of organic iodine compounds into the atmosphere, accumulation of iodine in living organisms, oxidation and reduction of inorganic iodine species, and sorption of iodine by soils and sediments. Considerable geochemical evidence has indicated that these processes are influenced or controlled by microbial activities, although the precise mechanisms involved are still unclear. This review summarizes current knowledge on interactions between microorganisms and iodine, with special emphasis on newly isolated bacteria possibly contributing to the cycling of iodine on a global scale.
Draft genome sequence of Arenibacter sp. Genome Announc. Gold dissolution from Ore with iodide-oxidising bacteria. Gold leaching from ore using iodide-iodine mixtures is an alternative to gold cyanidation. This study evaluated the ability of iodide-oxidising bacteria to solubilise gold from ore that was mainly composed of gold, pyrite, galena, and chalcopyrite. Eight bacterial strains were successfully isolated from brine. Those strains were incubated in a liquid culture medium containing ore with a gold content of 0.
The gold was solubilised completely within 30 days of incubation in the iodine-iodide lixiviant solution generated by three bacterial strains. One strain, in particular, completed the dissolution of gold within 5 days of incubation and was identified as a member of the genus Roseovarius. Thus, the possibility of bacterial gold leaching using iodide-oxidising bacteria was successfully demonstrated.
Bioleaching gold with iodide would likely be more environmentally sustainable than traditional cyanide leaching. Further research is required to evaluate the techno-economic feasibility of this approach.
The behaviour of iodine and bromine in estuarine surface sediments. The distribution of I and Br was examd. The I and Br concns. In the Loch Etive a Sjordic estuary on the west coast of Scotland sediments both Br and I can be used as an indicator of marine org. This suggests that the mechanism of incorporation of I by seston previously proposed is probably an important pathway to sediments.
The similarity of Br assocn. Nickel requirement and factor F content of methanogenic bacteria. Methanobacterium thermoautotrophicum Has been reported to require Ni for growth and to contain high concns. All methanogenic bacteria investigated incorporated Ni during growth and also synthesized factor F This was also true for Methanobrevibacter smithii, which is dependent on acetate as a C source, and for Methanosarcina barkeri growing on acetate or MeOH as energy sources.
Other bacteria, including Acetobacterium woodii and Clostridium thermoaceticum, contained no factor F It is further shown that 2 yellow Ni-contg. Structure of an F variant from archaea associated with anaerobic oxidation of methane. Microbial mats collected at cold methane seeps in the Black Sea carry out anaerobic oxidn. Mass spectrometry of mat samples revealed the presence of two nickel-contg. The two cofactors were isolated and purified, and their constitution and abs.
The corresponding diastereoisomeric pentaacids could also be sepd. Equilibration of the pentaacids under acid catalysis showed that the S isomer is the naturally occurring albeit thermodynamically less stable one. Regional variation of CH 4 and N 2 production processes in the deep aquifers of an accretionary prism.
Microbes and environments , 31 3 , ISSN:. Accretionary prisms are mainly composed of ancient marine sediment scraped from the subducting oceanic plate at a convergent plate boundary.
Large amounts of anaerobic groundwater and natural gas, mainly methane CH4 and nitrogen gas N2 , are present in the deep aquifers associated with an accretionary prism; however, the origins of these gases are poorly understood. We herein revealed regional variations in CH4 and N2 production processes in deep aquifers in the accretionary prism in Southwest Japan, known as the Shimanto Belt.
Stable carbon isotopic and microbiological analyses suggested that CH4 is produced through the non-biological thermal decomposition of organic matter in the deep aquifers in the coastal area near the convergent plate boundary, whereas a syntrophic consortium of hydrogen H2 -producing fermentative bacteria and H2-utilizing methanogens contributes to the significant production of CH4 observed in deep aquifers in midland and mountainous areas associated with the accretionary prism.
Our results also demonstrated that N2 production through the anaerobic oxidation of organic matter by denitrifying bacteria is particularly prevalent in deep aquifers in mountainous areas in which groundwater is affected by rainfall. Fossil methane source dominates Cariaco Basin water column methane geochemistry. American Geophysical Union. Natural radiocarbon measurements on methane 14C-CH4 extd. Previous work on Cariaco Basin methane CH4 considered only a diagenetic sediment source.
Sediment CH4 is produced from modern particulate material; thus the sediment and water column CH4 have distinct sources. Using time-dependent CH4 geochem. Oxidizing this CH4 to dissolved inorg. Carbon age and chemical evolution of Ca HCO 3 2 -type groundwater of age less than 8, years in a confined sandy and muddy Pleistocene aquifer.
The isotopic composition of atmospheric methane. Global Biogeochem. CH4 from air samples collected during oceanog. Water Resour. Schwab, Valerie F. All incubations were carried out at least in triplicates. Methane, hydrogen and acetate concentrations were continuously monitored over a period of 6 months and analysed by GC as described above. Three parallel extractions were carried out, and extracts were pooled for each incubation treatment.
DNA concentration and purity were determined by standard agarose gel electrophoresis and fluorometrically using RiboGreen Qubit Assay Kit, Invitrogen according to the manufacturer's instructions. The PCR amplicons were purified using the Qia quick purification kit Qiagen in accordance with the manufacturer's instructions and quantified using RiboGreen. Quantitative PCR was used to determine bacterial and archaeal abundances in the original sediment core and river water samples.
Bacterial and archael targets were measured in at least three different dilutions of DNA extracts 1 : 10—1 : and in triplicate. Primer sets specific for different phylogenetic domains and functional genes mcrA , dsrA were used according to Beckmann et al. The specificity of the reactions was confirmed by melting curve analysis and agarose gel electrophoresis to identify unspecific PCR products.
Amplification efficiencies for all reactions ranged from Resulting sequences were checked for quality and sequences shorter than base pairs were discarded using mothur Schloss et al.
Chimeras were checked using Uchime algorithm Edgar et al. Sediment cores A—C were taken at three different sites that were not exposed to strong river current and characterized by the influence of the dominant Eucalyptus vegetation.
Investigations of the sediment cores revealed highly similar lithologic profiles, with an upper layer comprised of Eucalyptus leaves 0—15 cm , an intermediate mixed layer containing Eucalyptus leaves and fine grainy sand including decomposed organic matter 15—25 cm and a mud layer at the bottom of the cores 25—50 cm Fig.
The mud layer corresponded to an average subsurface methane production rate of 6. Maximum rates of methane production were observed in 40 cm sediment depth Fig. Methane-containing gas bubbles were ubiquitous in the sand and mud layer suggesting a methane-saturated state of the muddy sediment. Nitrate and sulphate concentrations of the river water and the sediment porewater were below the detection limit. However, high dissolved iron concentrations were obtained to a depth of 35 cm where methanogenic processes were detected Fig.
The river water above the sediment cores showed a slightly decreased pH of 6. Stable carbon and hydrogen isotope values of the methane produced in situ in the river sediment and in the methanogenic enrichments. Depth profile from three different sediment cores from the Tootie River sediment A—C. River sediment covered with Eucalyptus leaves releasing gas bubbles containing methane 1—2. Sediment slurries from the cores A—C and river water were collected aseptically and incubated anaerobically under in situ conditions without substrate for an incubation time over 6 months.
Whilst no methane emissions were observed in water samples, all river sediment incubations showed a constant and long-term formation of methane Fig. No methane or hydrogen release was observed in the sterile control or the incubations with the methanogenic inhibitor 2-Bromoethanesulphonate, thus excluding an abiotic degassing of adsorbed methane from the incubated samples. Sediment slurries were amended with methanogenic substrates to evaluate the methanogenic potential in the river sediment.
The addition of acetate to the incubations leads to an initial strong and relatively rapid stimulation of methane production, whilst the production yield over a period of 6 months was less pronounced compared with the enrichments amended with methylated substrates Fig.
However, the commencement of methane formation was preceded by a shorter lag phase when acetate was added as methanogenic substrate. In the unamended cultures, small amounts of acetate up to 0. To assess the abundance of selected groups, quantitative PCR was performed on the different sections of the sediment cores Fig. Similar to minor variations in the methane gradients between replicate cores, total cell counts in all cores differed only slightly, although strong depth-dependent trends were observed as revealed by fluorescence microscopy Fig.
Cell numbers increased with sediment depth, peaking in the transition zone where the mud sediment starts and Eucalyptus leaves are still present 20—25 cm sediment depth as well as in the methanogenic zone 35 cm sediment depth. Total cell counts were within the same range as the cell numbers determined by quantitative PCR. The ratio of archaeal to bacterial cell numbers generally decreased from the surface 1 : —1 : 10 at a depth of 40 cm in the methanogenic zone.
Estimated bacterial numbers were highest in the sandy zone containing Eucalyptus leaves and decomposed organic matter, whereas archaeal numbers peaked at a depth of 40 cm characterized by highest methane-formation rates. Bacterial cell numbers strongly decreased within the methanogenic layer. The abundances of the methyl-coenzyme M reductase gene mcrA , representative for methanogenic archaea generally, correlated well with those of the archaeal 16S rRNA genes.
For the quantitative detection of the sulphate reducing bacteria, the dissimilatory sulphite reductase gene dsrA was targeted. Consistently low abundances of sulphate reducers 0. No sulphate-reducing genes were detected in the water column of the river. Specific 16S rRNA gene primer sets were applied for the differentiation of the Methanosarcinales and the Crenarchaeota. Furthermore, the quantification of mcrA genes as a proxy for methanogenic archaea showed that Methanosarcinales accounted for most of the methanogens.
A total of 8 different methanogenic archaeal species were obtained. Most of them were related to obligate and facultatively acetocalstic Methanosarcinales Methanosaeta spp. Typical Methanosarcina cell aggregates of these species were also present in the original sediment and the enrichment cultures.
However, relatives of Methanosarcina spp. Methylotrophic methanogens were specifically enriched in the methanol and methylamine-amended cultures and represented by Methanomethylovorans spp. The results of the archaeal community analysis confirmed that acetoclastic methanogens play a central role in the methane-formation process in the river sediments and methylotrophic methanogens were selectively enriched in specifically designed culture media.
Interestingly, unclassified Methanomicrobia have been detected in the original samples and showed a high abundance in the unamended and hydrogenotrophic enrichments. Sequences originating from uncultured Crenarchaeota were observed in the gas releasing river sediment but with major abundance in the river water column Fig.
The crenarchaeal sequences belonged to Thermofilum sp. Surprisingly, the unclassified Crenarchaeota could be enriched in the acetate and methanol amendments of the river sediment. The detected Gram-positive bacteria exclusively belonged to the Firmicutes Fig. The majority of the microbial community was represented by bacterial species that are potentially capable of hydrocarbon utilization and were closely related to Pseudomonas spp.
Clostridium spp. Interestingly, members of the Chloroflexi affiliated with Dehalogenimonas spp. Furthermore, relatives of sulphate-reducing bacteria were detected in the river sediment from 25 to 40 cm sediment depth and enrichment cultures but less abundant in the water column.
In summary, potential hydrocarbon-degrading bacteria including a high relative abundance of unclassified members dominate the bacterial communities in the methanogenic river sediments. The river sediments examined are characterized by high levels of organic matter input from the prevalent Eucalyptus vegetation, that is fuelling microbial activity in the upper sediment layers.
As a result, oxygen is depleted within the uppermost few centimetres, and anoxic conditions prevail beneath this layer. Our results revealed that acetoclastic methane formation is the terminal major pathway for organic matter degradation in this pristine hydrocarbon-rich river system.
The high amount of methane in the sediment resulted from the activity and abundance of methanogenic archaea that match well with the average range observed in river sediments Heyer, ; Jiang et al.
Acetoclastic methanogenesis was mainly carried out by Methanosaeta spp. Furthermore, previous studies showed that acetate-utilizing methanogens are more sensitive to high ammonia concentrations than hydrogenotrophic methanogens preventing the growth of Methanosaeta spp. The low ammonia concentrations in the river sediments might favour the growth of Methanosaeta spp.
Acetate accelerated in vitro methanogenesis rapidly and markedly characterized by the smallest lag phase indicating the absence of substrate competition with sulphate-reducing bacteria. Low concentrations of acetate and hydrogen in situ are in agreement with their proposed role as key intermediates during methanogenesis maintained from the degradation processes of natural organic compounds and hydrocarbons Zengler et al.
Earlier studies observed the predominance of acetoclastic methanogenesis in sediments related to high organic matter pools as well as high in situ temperatures resulting in a significant activation of organic matter degradation Wellsbury et al. One of the most striking differences between the pristine hydrocarbon-rich river sediments and previously investigated river sediments is the complete absence of sulphate. Gaspar, J. Microbial dynamics and control in shale gas production.
Gauthier, M. Marinobacter hydrocarbonoclasticus gen. Goldman, P. Carbon-halogen bond cleavage III. Studies on bacterial halidohydrolases. Haluszczak, L. Harkness, J. The geochemistry of naturally occurring methane and saline groundwater in an area of unconventional shale gas development.
Iodide, bromide, and ammonium in hydraulic fracturing and oil and gas wastewaters: environmental implications. Hayes, T. Heilweil, V. Gas-tracer experiment for evaluating the fate of methane in a coastal plain stream: degassing versus in-stream oxidation. Houlton, B. A unifying framework for dinitrogen fixation in the terrestrial biosphere. Huntemann, M. Genomic Sci. Huu, N. Marinobacter aquaeolei sp. Hyatt, D. Gene and translation initiation site prediction in metagenomic sequences.
Bioinformatics 28, — Kanehisa, M. KEGG: Kyoto encyclopedia of genes and genomes. Kang, M. Identification and characterization of high methane-emitting abandoned oil and gas wells. Kerr, R. Natural gas from shale bursts onto the scene. Science , — Kim, H. Arcobacter marinus sp. Klatt, J. Assessment of the stoichiometry and efficiency of CO 2 fixation coupled to reduced sulfur oxidation. Kutvonen, H. Nitrate and ammonia as nitrogen sources for deep subsurface microorganisms.
Lester, Y. Characterization of hydraulic fracturing flowback water in Colorado: implications for water treatment. Total Environ. Liang, R. Metabolic capability of a predominant Halanaerobium sp. Lipus, D. Microbial communities in Bakken region produced water. FEMS Microbiol. Predominance and metabolic potential of Halanaerobium in produced water from hydraulically fractured Marcellus shale wells.
Luek, J. Temporal dynamics of halogenated organic compounds in Marcellus Shale flowback. Water Res. Makarova, K. Mars, A. Microbial degradation of chloroaromatics: use of the meta-cleavage pathway for mineralization of chlorobenzene. Miller, C. EMIRGE: reconstruction of full-length ribosomal genes from microbial community short read sequencing data. Genome Biol. Mohan, A. Microbial community changes in hydraulic fracturing fluids and produced water from shale gas extraction.
Moore, M. Differentiating between biogenic and thermogenic sources of natural gas in coalbed methane reservoirs from the Illinois Basin using noble gas and hydrocarbon geochemistry. Mounier, J. The marine bacterium Marinobacter hydrocarbonoclasticus SP17 degrades a wide range of lipids and hydrocarbons through the formation of oleolytic biofilms with distinct gene expression profiles.
Mouser, P. Hydraulic fracturing offers view of microbial life in the deep terrestrial subsurface. Nixon, S. Guar gum stimulates biogenic sulfide production at elevated pressures: implications for shale gas extraction. Noble, R. Oren, A. Microbial life at high salt concentrations: phylogenetic and metabolic diversity.
Saline Systems Panescu, J. Draft genome sequences of two chemosynthetic Arcobacter strains isolated from hydraulically fractured wells in marcellus and Utica shales.
Genome Announc. Patel, A. Virus and prokaryote enumeration from planktonic aquatic environments by epifluorescence microscopy with SYBR Green I. Pirzadeh, P. Hydraulic fracturing additives and the delayed onset of hydrogen sulfide in shale gas. Energy Fuels 28, — Quevillon, E.
InterProScan: protein domains identifier. Roalkvam, I. Physiological and genomic characterization of Arcobacter anaerophilus IR-1 reveals new metabolic features in Epsilonproteobacteria. Russell, A. Type VI secretion system effectors: poisons with a purpose.
Singer, E. Struchtemeyer, C. Bacterial communities associated with hydraulic fracturing fluids in thermogenic natural gas wells in North Central Texas, USA. Tour, J. Green carbon as a bridge to renewable energy. Tummings, S. Draft genome sequences of Marinobacter strains recovered from Utica shale-produced fluids. Vaysse, P. Proteomic analysis of Marinobacter hydrocarbonoclasticus SP17 biofilm formation at the alkane-water interface reveals novel proteins and cellular processes involved in hexadecane assimilation.
Veenagayathri, K. Ortho and meta cleavage dioxygenases detected during the degradation of phenolic compounds by a moderately halophilic bacterial consortium. Vengosh, A. The geochemistry of hydraulic fracturing fluids.
Earth Planet. Vidic, R. Impact of shale gas development on regional water quality. Science Voordouw, G. Dahl and C. Friedrich Berlin: Springer , — Sulfide remediation by pulsed injection of nitrate into a low temperature Canadian heavy oil reservoir. To synthesize ATP, Thermoproteus spp.
The phylum Euryarchaeota includes several distinct classes. Species in the classes Methanobacteria, Methanococci, and Methanomicrobia represent Archaea that can be generally described as methanogens. Methanogens are unique in that they can reduce carbon dioxide in the presence of hydrogen, producing methane. They can live in the most extreme environments and can reproduce at temperatures varying from below freezing to boiling.
Methanogens have been found in hot springs as well as deep under ice in Greenland. Some scientists have even hypothesized that methanogens may inhabit the planet Mars because the mixture of gases produced by methanogens resembles the makeup of the Martian atmosphere.
Some genera of methanogens, notably Methanosarcina , can grow and produce methane in the presence of oxygen, although the vast majority are strict anaerobes. Halobacteria require a very high concentrations of sodium chloride in their aquatic environment.
One remarkable feature of these organisms is that they perform photosynthesis using the protein bacteriorhodopsin , which gives them, and the bodies of water they inhabit, a beautiful purple color Figure 2. Figure 2.
Halobacteria growing in these salt ponds gives them a distinct purple color. Notable species of Halobacteria include Halobacterium salinarum , which may be the oldest living organism on earth; scientists have isolated its DNA from fossils that are million years old.
Archaea are not known to cause any disease in humans, animals, plants, bacteria, or in other archaea. Although this makes sense for the extremophiles, not all archaea live in extreme environments. Many genera and species of Archaea are mesophiles, so they can live in human and animal microbiomes, although they rarely do. As we have learned, some methanogens exist in the human gastrointestinal tract. Yet we have no reliable evidence pointing to any archaean as the causative agent of any human disease.
0コメント