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ABSTRACT: Members of Sulfurihydrogenibium are often observed as visible filamentous biomass in circumneutral hot springs and play roles in sulfur-cycling, hydrogen oxidation and iron mineralization. To gain insight into the ecophysiology of Sulfurihydrogenibium populations, we conducted preliminary metatranscriptomic analysis of three distinct thermal springs; Calcite Springs (YNP-CS) and Mammoth Springs (YNP-MHS) in Yellowstone National Park, USA, and Furnas Springs (AZ) in Azores, Portugal. Genes to which transcripts were assigned revealed commonly expressed functions among the sites, while several differences were also observed. All three sites, Sulfurihydrogenibium spp. dominate and are obtaining energy via metabolism of sulfur compounds under microaerophilic conditions. Cell motility was one of the expressed functions in two sites (YNP-CS and AZ) with slower stream flow rates and thicker well-formed biofilms. The transcripts from YNP-CS and -MHS exhibited varying levels of sequence divergence from the reference genomes and corresponding metagenomes, suggesting the presence of microdiversity among Sulfurihydrogenibium populations in situ. Conversely, the majority of the AZ transcripts were identical to the S. azorense genome. Our initial results show that the metatranscriptomes in these similar Aquificales-dominated communities can reveal community-level gene function in geochemically distinct thermal environments.
Environmental Microbiology 12/2012; · 5.84 Impact Factor
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ABSTRACT: Cultivation-independent studies have shown that taxa belonging to the "deep-sea hydrothermal vent euryarchaeota 2" (DHVE2) lineage are widespread at deep-sea hydrothermal vents. While this lineage appears to be a common and important member of the microbial community at vent environments, relatively little is known about their overall distribution and phylogenetic diversity. In this study, we examined the distribution, relative abundance, co-occurrence patterns, and phylogenetic diversity of cultivable thermoacidophilic DHVE2 in deposits from globally distributed vent fields. Results of quantitative polymerase chain reaction assays with primers specific for the DHVE2 and Archaea demonstrate the ubiquity of the DHVE2 at deep-sea vents and suggest that they are significant members of the archaeal communities of established vent deposit communities. Local similarity analysis of pyrosequencing data revealed that the distribution of the DHVE2 was positively correlated with 10 other Euryarchaeota phylotypes and negatively correlated with mostly Crenarchaeota phylotypes. Targeted cultivation efforts resulted in the isolation of 12 axenic strains from six different vent fields, expanding the cultivable diversity of this lineage to vents along the East Pacific Rise and Mid-Atlantic Ridge. Eleven of these isolates shared greater than 97% 16S rRNA gene sequence similarity with one another and the only described isolate of the DHVE2, Aciduliprofundum boonei T469(T). Sequencing and phylogenetic analysis of five protein-coding loci, atpA, EF-2, radA, rpoB, and secY, revealed clustering of isolates according to geographic region of isolation. Overall, this study increases our understanding of the distribution, abundance, and phylogenetic diversity of the DHVE2.
Frontiers in microbiology. 01/2012; 3:47.
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ABSTRACT: Thirteen novel, obligately anaerobic, thermoacidophilic bacteria were isolated from deep-sea hydrothermal vent sites. Four of the strains, designated EP5-r(T), KM1, Mar08-272r(T) and Mar08-368r, were selected for metabolic and physiological characterization. With the exception of strain EP5-r(T), all strains were short rods that grew between 40 and 72 °C, with optimal growth at 60-65 °C. Strain EP5-r(T) was more ovoid in shape and grew between 45 and 75 °C, with optimum growth at 60 °C. The pH range for growth of all the isolates was between pH 3.5 and 5.5 (optimum pH 4.5 to 5.0). Strain Mar08-272r(T) could only grow up to pH 5.0. Elemental sulfur was required for heterotrophic growth on acetate, succinate, Casamino acids and yeast extract. Strains EP5-r(T), Mar08-272r(T) and Mar08-368r could also use fumarate, while strains EP5-r(T), KM1 and Mar08-272r(T) could also use propionate. All isolates were able to grow chemolithotrophically on H(2), CO(2), sulfur and vitamins. Phylogenetic analysis of 16S rRNA gene sequences placed all isolates within the family Desulfurellaceae of the class Deltaproteobacteria, with the closest cultured relative being Hippea maritima MH(2)(T) (~95-98 % gene sequence similarity). Phylogenetic analysis also identified several isolates with at least one intervening sequence within the 16S rRNA gene. The genomic DNA G+C contents of strains EP5-r(T), KM1, Mar08-272r(T) and Mar08-368r were 37.1, 42.0, 35.6 and 37.9 mol%, respectively. The new isolates differed most significantly from H. maritima MH(2)(T) in their phylogenetic placement and in that they were obligate thermoacidophiles. Based on these phylogenetic and phenotypic properties, the following two novel species are proposed: Hippea jasoniae sp. nov. (type strain Mar08-272r(T) = DSM 24585(T) = OCM 985(T)) and Hippea alviniae sp. nov. (type strain EP5-r(T) = DSM 24586(T) = OCM 986(T)).
INTERNATIONAL JOURNAL OF SYSTEMATIC AND EVOLUTIONARY MICROBIOLOGY 07/2011; 62(Pt 6):1252-8. · 2.11 Impact Factor
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Gilberto E Flores,
James H Campbell,
Julie D Kirshtein,
Jennifer Meneghin,
Mircea Podar,
Joshua I Steinberg,
Jeffrey S Seewald,
Margaret Kingston Tivey,
Mary A Voytek,
Zamin K Yang, Anna-Louise Reysenbach
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ABSTRACT: To evaluate the effects of local fluid geochemistry on microbial communities associated with active hydrothermal vent deposits, we examined the archaeal and bacterial communities of 12 samples collected from two very different vent fields: the basalt-hosted Lucky Strike (37°17'N, 32°16.3'W, depth 1600-1750 m) and the ultramafic-hosted Rainbow (36°13'N, 33°54.1'W, depth 2270-2330 m) vent fields along the Mid-Atlantic Ridge (MAR). Using multiplexed barcoded pyrosequencing of the variable region 4 (V4) of the 16S rRNA genes, we show statistically significant differences between the archaeal and bacterial communities associated with the different vent fields. Quantitative polymerase chain reaction (qPCR) assays of the functional gene diagnostic for methanogenesis (mcrA), as well as geochemical modelling to predict pore fluid chemistries within the deposits, support the pyrosequencing observations. Collectively, these results show that the less reduced, hydrogen-poor fluids at Lucky Strike limit colonization by strict anaerobes such as methanogens, and allow for hyperthermophilic microaerophiles, like Aeropyrum. In contrast, the hydrogen-rich reducing vent fluids at the ultramafic-influenced Rainbow vent field support the prevalence of methanogens and other hydrogen-oxidizing thermophiles at this site. These results demonstrate that biogeographical patterns of hydrothermal vent microorganisms are shaped in part by large scale geological and geochemical processes.
Environmental Microbiology 03/2011; 13(8):2158-71. · 5.84 Impact Factor
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ABSTRACT: A thermophilic bacterium, designated strain CR11(T), was isolated from a filamentous sample collected from a terrestrial hot spring on the south-western foothills of the Rincón volcano in Costa Rica. The Gram-negative cells are approximately 2.4-3.9 microm long and 0.5-0.6 microm wide and are motile rods with polar flagella. Strain CR11(T) grows between 65 and 85 degrees C (optimum 75 degrees C, doubling time 4.5 h) and between pH 4.8 and 7.8 (optimum pH 5.9-6.5). The isolate grows chemolithotrophically with S(0), S(2)O(2)(3)(-) or H(2) as the electron donor and with O(2) (up to 16 %, v/v) as the sole electron acceptor. The isolate can grow on mannose, glucose, maltose, succinate, peptone, Casamino acids, starch, citrate and yeast extract in the presence of oxygen (4 %) and S(0). Growth occurs only at NaCl concentrations below 0.4 % (w/v). The G+C content of strain CR11(T) is 40.3 mol%. Phylogenetic analysis of the 16S rRNA gene sequence places the strain as a close relative of Thermocrinis ruber OC 1/4(T) (95.7 % sequence similarity). Based on phylogenetic and physiological characteristics, we propose the name Thermocrinis minervae sp. nov., with CR11(T) (=DSM 19557(T) =ATCC BAA-1533(T)) as the type strain.
International journal of systematic and evolutionary microbiology 09/2009; 60(Pt 2):338-43. · 2.27 Impact Factor
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ABSTRACT: Four thermophilic, sulfur-oxidizing, chemolithoautotrophic strains with >99 % 16S rRNA gene sequence similarity were isolated from terrestrial hot springs in the Geyser Valley and the Uzon Caldera, Kamchatka, Russia. One strain, designated UZ3-5T, was characterized fully. Cells of UZ3-5T were Gram-negative, motile, slightly oval rods (about 0.7 microm wide and 1.0 microm long) with multiple polar flagella. All four strains were obligately microaerophilic chemolithoautotrophs and could use elemental sulfur or thiosulfate as electron donors and oxygen (1-14 %, v/v) as the electron acceptor. Strain UZ3-5T grew at temperatures between 55 and 80 degrees C (optimally at 75 degrees C; 1.1 h doubling time), at pH 5.0-7.2 (optimally at pH 6.0-6.3) and at 0-0.9 % NaCl (optimally in the absence of NaCl). The G+C content of the genomic DNA of strain UZ3-5T was 35 mol%. Phylogenetic analysis revealed that strain UZ3-5T was a member of the genus Sulfurihydrogenibium, its closest relative in culture being Sulfurihydrogenibium azorense Az-Fu1T (98.3 % 16S rRNA gene sequence similarity). On the basis of its physiological and molecular characteristics, strain UZ3-5T represents a novel species of the genus Sulfurihydrogenibium, for which the name Sulfurihydrogenibium rodmanii sp. nov. is proposed. The type strain is UZ3-5T (=OCM 900T =ATCC BAA-1536T =DSM 19533T).
International journal of systematic and evolutionary microbiology 05/2008; 58(Pt 5):1147-52. · 2.27 Impact Factor
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ABSTRACT: Three thermophilic, aerobic, hydrogen- and sulfur-oxidizing bacteria were isolated from an Icelandic hot spring near the town of Hveragerdi and share >99 % 16S rRNA gene sequence similarity. One of these isolates, designated strain I6628T, was selected for further characterization. Strain I6628T is a motile rod, 1.5-2.5 microm long and about 0.5 microm wide. Growth occurred between 40 and 73 degrees C (optimally at 68 degrees C), at pH 5.3-7.8 (optimally at pH 6.6) and at NaCl concentrations between 0 and 0.5 % (w/v). Strain I6628T grew with H2, S0 or S2O3(2-) as an electron donor with O2 (up to 25 %, v/v; optimally at 4-9 %) as the sole electron acceptor. CO2 and succinate were utilized as carbon sources but no organic compounds, including succinate, could be used as an energy source. The G+C content of the genomic DNA was determined to be 28.1 mol%. Phylogenetic analysis of the 16S rRNA gene sequence indicated that strain I6628T is a member of the genus Sulfurihydrogenibium, the closest cultivated relative being the recently described strain Sulfurihydrogenibium rodmanii UZ3-5T (98.2 % sequence similarity). On the basis of the physiology and phylogeny of this organism, strain I6628T represents a novel species of the genus Sulfurihydrogenibium, for which the name Sulfurihydrogenibium kristjanssonii sp. nov. is proposed. The type strain is I6628T (=DSM 19534T =OCM 901T =ATCC BAA-1535T).
International journal of systematic and evolutionary microbiology 05/2008; 58(Pt 5):1153-8. · 2.27 Impact Factor
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ABSTRACT: Thermocouple arrays were deployed on two deep-sea hydrothermal vents at Guaymas Basin (27 degrees 0.5'N, 111 degrees 24.5'W) in order to measure in situ temperatures at which microorganisms colonize the associated mineral deposits. Intact sections of three structures that formed around the arrays were collected after 4 and 72 day deployments (named BM4, BM72 and TS72). Archaeal diversity associated with discreet subsamples collected across each deposit was determined by polymerase chain reaction amplification of 16S rRNA genes. Spatial differences in archaeal diversity were observed in all deposits and appeared related to in situ temperature. In BM4, no 16S rRNA genes were detected beyond about 1.5 cm within the sample (> 200 degrees C). Phylotypes detected on the outside of this deposit belong to taxonomic groups containing mesophiles and (hyper)thermophiles, whereas only putative hyperthermophiles were detected 1.5 cm inside the structure (approximately 110 degrees C). In contrast, the more moderate thermal gradient recorded across TS72 was associated with a deeper colonization (2-3 cm inside the deposit) of putative hyperthermophilic phylotypes. Although our study does not provide a precise assessment of the highest temperature for the existence of microbial habitats inside the deposits, archaeal 16S rRNA genes were detected directly next to thermocouples that measured 110 degrees C (Methanocaldococcus spp. in BM4) and 116 degrees C (Desulfurococcaceae in TS72). The successive array deployments conducted at the Broken Mushroom (BM) site also revealed compositional differences in archaeal communities associated with immature (BM4) and mature chimneys (BM72) formed by the same fluids. These differences suggest a temporal transition in the primary carbon sources used by the archaeal communities, with potential CO(2)/H(2) methanogens prevalent in BM4 being replaced by possible methylotroph or acetoclastic methanogens and heterotrophs in BM72. This study is the first direct assessment of in situ conditions experienced by microorganisms inhabiting actively forming hydrothermal deposits at different stages of structure development.
Environmental Microbiology 04/2008; 10(4):874-84. · 5.84 Impact Factor
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ABSTRACT: The lipid composition of Candidatus "Aciduliprofundum boonei", the only cultivated representative of archaea falling in the DHVE2 phylogenetic cluster, a group of microorganisms ubiquitously occurring at hydrothermal vents, was studied. The predominant core membrane lipids in this thermophilic euryarchaeote were found to be composed of glycerol dibiphytanyl glycerol tetraethers (GDGTs) containing 0-4 cyclopentyl moieties. In addition, GDGTs with an additional covalent bond between the isoprenoid hydrocarbon chains, so-called H-shaped GDGTs, were present. The latter core lipids have been rarely reported previously. Intact polar lipid analysis revealed that they predominantly consist of GDGTs with a phospho-glycerol headgroup.
Extremophiles 02/2008; 12(1):119-24. · 2.94 Impact Factor
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ABSTRACT: Glycerol dialkyl glycerol tetraethers (GDGTs) are core membrane lipids originally thought to be produced mainly by (hyper)thermophilic archaea. Environmental screening of low-temperature environments showed, however, the abundant presence of structurally diverse GDGTs from both bacterial and archaeal sources. In this study, we examined the occurrences and distribution of GDGTs in hot spring environments in Yellowstone National Park with high temperatures (47 to 83 degrees C) and mostly neutral to alkaline pHs. GDGTs with 0 to 4 cyclopentane moieties were dominant in all samples and are likely derived from both (hyper)thermophilic Crenarchaeota and Euryarchaeota. GDGTs with 4 to 8 cyclopentane moieties, likely derived from the crenarchaeotal order Sulfolobales and the euryarchaeotal order Thermoplasmatales, are usually present in much lower abundance, consistent with the relatively high pH values of the hot springs. The relative abundances of cyclopentane-containing GDGTs did not correlate with in situ temperature and pH, suggesting that other environmental and possibly genetic factors play a role as well. Crenarchaeol, a biomarker thought to be specific for nonthermophilic group I Crenarchaeota, was also found in most hot springs, though in relatively low concentrations, i.e., <5% of total GDGTs. Its abundance did not correlate with temperature, as has been reported previously. Instead, the cooccurrence of relatively abundant nonisoprenoid GDGTs thought to be derived from soil bacteria suggests a predominantly allochthonous source for crenarchaeol in these hot spring environments. Finally, the distribution of bacterial branched GDGTs suggests that they may be derived from the geothermally heated soils surrounding the hot springs.
Applied and Environmental Microbiology 10/2007; 73(19):6181-91. · 3.83 Impact Factor
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ABSTRACT: Over the past few decades the extremes at which life thrives has continued to challenge our understanding of biochemistry, biology and evolution. As more new extremophiles are brought into laboratory culture, they have provided a multitude of potential applications for biotechnology. More recently, innovative culturing approaches, environmental genome sequencing and whole genome sequencing have provided new opportunities for the biotechnological exploration of extremophiles.
Current Opinion in Biotechnology 07/2006; 17(3):250-5. · 7.71 Impact Factor
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ABSTRACT: Deep-sea hydrothermal vents are important in global biogeochemical cycles, providing biological oases at the sea floor that are supported by the thermal and chemical flux from the Earth's interior. As hot, acidic and reduced hydrothermal fluids mix with cold, alkaline and oxygenated sea water, minerals precipitate to form porous sulphide-sulphate deposits. These structures provide microhabitats for a diversity of prokaryotes that exploit the geochemical and physical gradients in this dynamic ecosystem. It has been proposed that fluid pH in the actively venting sulphide structures is generally low (pH < 4.5), yet no extreme thermoacidophile has been isolated from vent deposits. Culture-independent surveys based on ribosomal RNA genes from deep-sea hydrothermal deposits have identified a widespread euryarchaeotal lineage, DHVE2 (deep-sea hydrothermal vent euryarchaeotic 2). Despite the ubiquity and apparent deep-sea endemism of DHVE2, cultivation of this group has been unsuccessful and thus its metabolism remains a mystery. Here we report the isolation and cultivation of a member of the DHVE2 group, which is an obligate thermoacidophilic sulphur- or iron-reducing heterotroph capable of growing from pH 3.3 to 5.8 and between 55 and 75 degrees C. In addition, we demonstrate that this isolate constitutes up to 15% of the archaeal population, providing evidence that thermoacidophiles may be key players in the sulphur and iron cycling at deep-sea vents.
Nature 07/2006; 442(7101):444-7. · 36.28 Impact Factor
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ABSTRACT: ABSTRACTA culture-independent molecular phylogenetic survey was carried out for a bacterial and archaeal community of a mineralized crust coating a sulphide spire, which was collected from the Edmond vent field (23° S, 69° E, 3300 m depth) on the Central Indian Ridge. Small-subunit rRNA genes (16S rDNA) were amplified from environmental DNA by PCR utilizing Bacteria-specific, and Archaea-specific 16S rDNA primers. PCR products were cloned and 26 bacterial and nine archaeal unique sequence types (phylotypes) were identified from 150 clones analysed by restriction fragment length polymorphism, representing eight and four distinct lineages, respectively. The majority (>90%) of the bacterial phylotypes group with the ɛ-Proteobacteria and confirms the global prevalence of ɛ-Proteobacteria in deep-sea hydrothermal environments. Among the ɛ-Proteobacteria, >40% of the phylotypes were closely related to the recently isolated deep-sea vent thermophilic chemolithoautotrophic sulphur-reducer, Nautilia lithotrophica. A single bacterial sequence was nearly identical (99% similarity) to the thermophilic hydrogen-oxidizing Hydrogenobacter thermolithotrophum, and is the first report of Hydrogenobacter at deep-sea hydrothermal vents. A majority (97%) of the archaeal phylotypes grouped with the ‘Deep-sea Hydrothermal Vent Euryarchaeotal Group’, a phylogenetic lineage of uncultured Archaea that have only been reported from other deep-sea hydrothermal vents on the Mid-Atlantic Ridge, East Pacific Rise, Juan de Fuca Ridge, Isu–Ogasawara Arc, Okinawa Trough and the Manus Basin. A single sequence was closely related to the hyperthermophilic sulphur-reducing Thermococcales frequently found in diverse deep-sea vent environments. Scanning electron micrographs of the mineralized crust reveal abundant filamentous, rod and coccoidal forms encased in sulphur and sulphide mineral precipitate, suggesting that the thermophilic chemolithoautorophs and sulphide-producing heterotrophs may influence the architecture and sulphur cycling of the sulphide spire.
Geobiology 09/2003; 1(2):119 - 127. · 4.11 Impact Factor
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ABSTRACT: To evaluate possible compositional changes in archaeal communities at a deep-sea hydrothermal vent field scale, we examined five different samples obtained after deploying in situ collectors for different times on three spatially separated venting sulphide structures on the East Pacific Rise (13 degrees N). Direct cell counts and whole-cell hybridizations with fluorescently labelled 16S rRNA-based oligonucleotide probes revealed that the relative abundance of archaeal populations represented from 14 to 33% of the prokaryotic community. 16S rDNA sequence analysis of the archaeal clone libraries indicated that a large percentage of clones were closely related to known archaeal isolates recovered from similar habitats. Among the 24 different phylotypes identified, Thermococcales-related sequences were dominant in all the libraries that also included representative genera of orders Methanopyrales, Methanococcales, Archaeoglobales and Desulfurococcales. The presence of most of these phylogenetic groups was confirmed in enrichment cultures performed at temperatures from 60 to 90 degrees C. Additional sequences with no known cultivated relatives grouped with the Marine group I Crenarchaeota, Korarchaeota and Deep-sea Hydrothermal Vent Euryarchaeota (DHVE) within which a novel lineage was identified. Furthermore, the archaeal community composition was distinct from vent to vent within the same vent field and varied within short time scales. This study provides new insights into microbial diversity and distribution at deep-sea hydrothermal vents.
Environmental Microbiology 07/2003; 5(6):492-502. · 5.84 Impact Factor
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ABSTRACT: A culture-independent molecular phylogenetic survey was carried out for a bacterial and archaeal community of a mineralized crust coating a sulphide spire, which was collected from the Edmond vent field (23 ° S, 69 ° E, 3300 m depth) on the Central Indian Ridge. Small-subunit rRNA genes (16S rDNA) were amplified from environmental DNA by PCR utilizing Bacteria-specific, and Archaea-specific 16S rDNA primers. PCR products were cloned and 26 bacterial and nine archaeal unique sequence types (phylotypes) were identified from 150 clones analysed by restriction fragment length polymorphism, representing eight and four distinct lineages, respectively. The majority (>90%) of the bacterial phylotypes group with the ε -Proteobacteria and confirms the global prevalence of ε -Proteobacteria in deep-sea hydrothermal environments. Among the ε -Proteobacteria, >40% of the phylotypes were closely related to the recently isolated deep-sea vent thermophilic chemolitho-autotrophic sulphur-reducer, Nautilia lithotrophica . A single bacterial sequence was nearly identical (99% similarity) to the thermophilic hydrogen-oxidizing Hydrogenobacter thermolithotrophum , and is the first report of Hydrogenobacter at deep-sea hydrothermal vents. A majority (97%) of the archaeal phylotypes grouped with the 'Deep-sea Hydrothermal Vent Euryarchaeotal Group', a phylogenetic lineage of uncultured Archaea that have only been reported from other deep-sea hydrothermal vents on the Mid-Atlantic Ridge, East Pacific Rise, Juan de Fuca Ridge, Isu–Ogasawara Arc, Okinawa Trough and the Manus Basin. A single sequence was closely related to the hyperthermophilic sulphur-reducing Thermococcales frequently found in diverse deep-sea vent environments. Scanning electron micrographs of the mineralized crust reveal abundant filamentous, rod and coccoidal forms encased in sulphur and sulphide mineral precipitate, suggesting that the thermophilic chemo-lithoautorophs and sulphide-producing heterotrophs may influence the architecture and sulphur cycling of the sulphide spire.
Geobiology 01/2003; 1:119-127. · 4.11 Impact Factor
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ABSTRACT: A thermophilic, non-spore-forming, marine, sulfate-reducing bacterium, strain SL6T, was isolated from deep-sea hydrothermal sulfides collected at Guaymas Basin. The gram-negative-staining cells occurred singly or in pairs as small, highly motile rods. The temperature range for growth was 50-80 degrees C with an optimum at 75 degrees C. The pH range for growth at 70 degrees C was 6.3-6.8, with an optimum at 6.5. The NaCl concentration range for growth was 5-55 g l(-1), with an optimum at 30 g l(-1). H2 and CO2 were the only substrates for growth and sulfate reduction. However, growth was stimulated by several organic compounds. Sulfur, thiosulfate, sulfite, cystine, nitrate and fumarate were not used as electron acceptors. Pyruvate, lactate and malate did not support fermentative growth. Desulfoviridin was not detected. The G+C content of the genomic DNA was 28 mol%. On the basis of 16S rRNA sequence analysis, strain SL6T is related to members of the genus Thermodesulfobacterium. However, the novel organism possesses phenotypic and phylogenetic traits that differ from those of its closest relatives. Therefore, it is proposed that this isolate, which constitutes the first marine representative of this genus, should be described as the type strain of a novel species, Thermodesulfobacterium hydrogeniphilum sp. nov. The type strain is SL6T (= DSM 14290T = JCM 11239T). Because of the phenotypic characteristics of the novel species, it is also proposed that the description of the genus Thermodesulfobacterium requires emendation.
International journal of systematic and evolutionary microbiology 06/2002; 52(Pt 3):765-72. · 2.27 Impact Factor
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ABSTRACT: A novel, regular to irregular, coccoid-shaped, anaerobic, Fe(III)-reducing microorganism was isolated from the Guaymas Basin hydrothermal system at a depth of 2000 m. Isolation was carried out with a new technique using Fe(III) oxide as the electron acceptor for the recovery of colonies on solid medium. The isolate, designated strain 234T, was strictly anaerobic and exhibited a tumbling motility. The cells had a single flagellum. Strain 234T grew at temperatures between 65 and 90 degrees C, with an optimum at about 88 degrees C. The optimal salt concentration for growth was around 19 g l(-1). The isolate was capable of growth with H2 as the sole electron donor coupled to the reduction of Fe(III) without the need for an organic carbon source. This is the first example of a dissimilatory Fe(III)-reducing micro-organism capable of growing autotrophically on hydrogen. In addition to molecular hydrogen, strain 234T oxidizes pyruvate, acetate, malate, succinate, peptone, formate, fumarate, yeast extract, glycerol, isoleucine, arginine, serine, glutamine, asparagine, stearate, palmitate, valerate, butyrate and propionate with the reduction of Fe(III). This isolate is the first example of a hyperthermophile capable of oxidizing long-chain fatty acids anaerobically. Isolate 234T grew exclusively with Fe(III) as the sole electron acceptor. The G+C content was 58.7 mol%. Based on detailed analysis of its 16S rDNA sequence, G+C content, distinguishing physiological features and metabolism, strain 234T is proposed to represent a novel genus within the Archaeoglobales. The name proposed for strain 234T is Geoglobus ahangari gen. nov., sp. nov..
International journal of systematic and evolutionary microbiology 06/2002; 52(Pt 3):719-28. · 2.27 Impact Factor
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ABSTRACT: Thermophilic microbial inhabitants of active seafloor and continental hot springs populate the deepest branches of the universal phylogenetic tree, making hydrothermal ecosystems the most ancient continuously inhabited ecosystems on Earth. Geochemical consequences of hot water-rock interactions render these environments habitable and supply a diverse array of energy sources. Clues to the strategies for how life thrives in these dynamic ecosystems are beginning to be elucidated through a confluence of biogeochemistry, microbiology, ecology, molecular biology, and genomics. These efforts have the potential to reveal how ecosystems originate, the extent of the subsurface biosphere, and the driving forces of evolution.
Science 06/2002; 296(5570):1077-82. · 31.20 Impact Factor
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ABSTRACT: It has recently been recognized that the ability to use Fe(III) as a terminal electron acceptor is a highly conserved characteristic in hyperthermophilic microorganisms. This suggests that it may be possible to recover as-yet-uncultured hyperthermophiles in pure culture if Fe(III) is used as an electron acceptor. As part of a study of the microbial diversity of the Obsidian Pool area in Yellowstone National Park, Wyo., hot sediment samples were used as the inoculum for enrichment cultures in media containing hydrogen as the sole electron donor and poorly crystalline Fe(III) oxide as the electron acceptor. A pure culture was recovered on solidified, Fe(III) oxide medium. The isolate, designated FW-1a, is a hyperthermophilic anaerobe that grows exclusively by coupling hydrogen oxidation to the reduction of poorly crystalline Fe(III) oxide. Organic carbon is not required for growth. Magnetite is the end product of Fe(III) oxide reduction under the culture conditions evaluated. The cells are rod shaped, about 0.5 microm by 1.0 to 1.2 microm, and motile and have a single flagellum. Strain FW-1a grows at circumneutral pH, at freshwater salinities, and at temperatures of between 65 and 100 degrees C with an optimum of 85 to 90 degrees C. To our knowledge this is the highest temperature optimum of any organism in the Bacteria. Analysis of the 16S ribosomal DNA (rDNA) sequence of strain FW-1a places it within the Bacteria, most closely related to abundant but uncultured microorganisms whose 16S rDNA sequences have been previously recovered from Obsidian Pool and a terrestrial hot spring in Iceland. While previous studies inferred that the uncultured microorganisms with these 16S rDNA sequences were sulfate-reducing organisms, the physiology of the strain FW-1a, which does not reduce sulfate, indicates that these organisms are just as likely to be Fe(III) reducers. These results further demonstrate that Fe(III) may be helpful for recovering as-yet-uncultured microorganisms from hydrothermal environments and illustrate that caution must be used in inferring the physiological characteristics of at least some thermophilic microorganisms solely from 16S rDNA sequences. Based on both its 16S rDNA sequence and physiological characteristics, strain FW-1a represents a new genus among the Bacteria. The name Geothermobacterium ferrireducens gen. nov., sp. nov., is proposed (ATCC BAA-426).
Applied and Environmental Microbiology 05/2002; 68(4):1735-42. · 3.83 Impact Factor
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ABSTRACT: A thermophilic, strictly anaerobic bacterium, designated strain SL1, was isolated from a deep, continental oil reservoir in
the East Paris Basin (France). This organism grew between 50 and 75°C, with an, optimum at 70°C. It was inhibited by elemental
sulfur and was able to reduce cystine and thiosulfate to hydrogen sulfide. The G+C content (40 mol%), the presence of a lipid
structure unique to the genusThermotoga, and the 16S rRNA sequence of strain SL1 indicated that the isolate belongs to the genusThermotoga. Based on DNA-DNA hybridization, isolate SL1 does not show species-level similarity with the recognized speciesT. maritima, T. neapolitana, andT. thermarum. Based on this description of strain SL1, we propose the recognition of a new species:Thermotoga subterranea.
Archives of Microbiology 04/1995; 164(2):91-97. · 1.43 Impact Factor
