Nitratiruptor tergarcus gen. nov., sp. nov. and Nitratifractor salsuginis gen. nov., sp. nov., nitrate-reducing chemolithoautotrophs of the ε-Proteobacteria isolated from a deep-sea hydrothermal system in the Mid-Okinawa Trough

2005 ◽  
Vol 55 (2) ◽  
pp. 925-933 ◽  
Author(s):  
Satoshi Nakagawa ◽  
Ken Takai ◽  
Fumio Inagaki ◽  
Koki Horikoshi ◽  
Yoshihiko Sako
Keyword(s):  
Deep Sea ◽  
Type Strain ◽  
Doubling Time ◽  
Okinawa Trough ◽  
Molecular Characteristics ◽  
Rrna Gene ◽  
Phylogenetic Groups ◽  
Ph Values ◽  
Low Concentrations ◽  
Optimum Ph

Two novel denitrifying bacteria, designated strains MI55-1T and E9I37-1T, were isolated from deep-sea hydrothermal vent chimney structures at the Iheya North hydrothermal field in the Mid-Okinawa Trough, Japan. Both isolates were strict chemolithoautotrophs growing by respiratory nitrate reduction with H2, forming N2 as a metabolic product. Oxygen (at low concentrations) could serve as an alternative electron acceptor for growth of the isolates. Growth of strain MI55-1T was observed at temperatures between 40 and 57 °C (optimum, 55 °C; doubling time, 2 h), at pH values between 5·4 and 6·9 (optimum, pH 6·4) and in the presence of between 1·5 and 4·0 % (w/v) NaCl (optimum, 2·5 %). Growth of strain E9I37-1T was observed at temperatures between 28 and 40 °C (optimum, 37 °C; doubling time, 2·5 h), at pH values between 5·6 and 7·6 (optimum, pH 7·0) and in the presence of between 1·5 and 3·5 % (w/v) NaCl (optimum, 3·0 %). The G+C contents of the genomic DNA of strains MI55-1T and E9I37-1T were 29·6 and 35·5 mol%, respectively. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strains MI55-1T and E9I37-1T belonged to groups A and F of the ε-Proteobacteria, but that they had distant phylogenetic relationships with any species, within the phylogenetic groups, that had validly published names (sequence similarities were less than 91 %). On the basis of the physiological and molecular characteristics of the novel isolates, it is proposed that they should each be classified in a novel genus: Nitratiruptor tergarcus gen. nov., sp. nov., with MI55-1T (=JCM 12459T=DSM 16512T) as the type strain, and Nitratifractor salsuginis gen. nov., sp. nov., with E9I37-1T (=JCM 12458T=DSM 16511T) as the type strain.

scholarly journals Sulfurimonas paralvinellae sp. nov., a novel mesophilic, hydrogen- and sulfur-oxidizing chemolithoautotroph within the Epsilonproteobacteria isolated from a deep-sea hydrothermal vent polychaete nest, reclassification of Thiomicrospira denitrificans as Sulfurimonas denitrificans comb. nov. and emended description of the genus Sulfurimonas

2006 ◽  
Vol 56 (8) ◽  
pp. 1725-1733 ◽  
Author(s):  
Ken Takai ◽  
Masae Suzuki ◽  
Satoshi Nakagawa ◽  
Masayuki Miyazaki ◽  
Yohey Suzuki ◽  
...  
Keyword(s):  
Deep Sea ◽  
Hydrothermal Vent ◽  
Type Strain ◽  
Elemental Sulfur ◽  
Okinawa Trough ◽  
Rrna Gene ◽  
Sulfur Source ◽  
The Novel ◽  
Emended Description ◽  
Thiomicrospira Denitrificans

A novel mesophilic bacterium, strain GO25T, was isolated from a nest of hydrothermal vent polychaetes, Paralvinella sp., at the Iheya North field in the Mid-Okinawa Trough. Cells were motile short rods with a single polar flagellum. Growth was observed between 4 and 35 °C (optimum 30 °C; 13–16 h doubling time) and between pH 5.4 and 8.6 (optimum pH 6.1). The isolate was a facultatively anaerobic chemolithoautotroph capable of growth using molecular hydrogen, elemental sulfur or thiosulfate as the sole energy source, carbon dioxide as the sole carbon source, ammonium or nitrate as the sole nitrogen source and elemental sulfur, thiosulfate or yeast extract as the sole sulfur source. Strain GO25T represents the first deep-sea epsilonproteobacterium capable of growth by both hydrogen and sulfur oxidation. Nitrate or molecular oxygen (up to 10 % partial pressure) could serve as the sole electron acceptor to support growth. Metabolic products of nitrate reduction shifted in response to the electron donor provided. The G+C content of genomic DNA was 37.6 mol%. Phylogenetic analysis based on 16S rRNA gene sequences indicated that the novel isolate belonged to the genus Sulfurimonas and was most closely related to Sulfurimonas autotrophica OK10T (96.3 % sequence similarity). DNA–DNA hybridization demonstrated that the novel isolate could be differentiated genotypically from Sulfurimonas autotrophica OK10T. On the basis of the physiological and molecular properties of the novel isolate, the name Sulfurimonas paralvinellae sp. nov. is proposed, with strain GO25T (=JCM 13212T=DSM 17229T) as the type strain. Thiomicrospira denitrificans DSM 1251T (=ATCC 33889T) is phylogenetically associated with Sulfurimonas autotrophica OK10T and Sulfurimonas paralvinellae GO25T. Based on the phylogenetic relationship between Thiomicrospira denitrificans DSM 1251T, Sulfurimonas autotrophica OK10T and Sulfurimonas paralvinellae GO25T, we propose the reclassification of Thiomicrospira denitrificans as Sulfurimonas denitrificans comb. nov. (type strain DSM 1251T=ATCC 33889T). In addition, an emended description of the genus Sulfurimonas is proposed.

scholarly journals Sphingosinithalassobacter tenebrarum sp. nov., isolated from a deep-sea cold seep

2020 ◽  
Vol 70 (10) ◽  
pp. 5561-5566 ◽  
Author(s):  
Rikuan Zheng ◽  
Chaomin Sun
Keyword(s):  
Phylogenetic Analysis ◽  
Deep Sea ◽  
Type Species ◽  
Cold Seep ◽  
Rrna Gene ◽  
Content Type ◽  
Ph Values ◽  
Link Type ◽  
Optimum Ph ◽  
Ubiquinone 10

A Gram-stain-negative, facultatively anaerobic, yellow-pigmented, non-motile, rod-shaped bacterium, designated zrk23T, was isolated from a deep-sea cold seep. The strain was characterized by a polyphasic approach to clarify its taxonomic position. Phylogenetic analysis based on 16S rRNA gene sequences placed zrk23T within the genus Sphingosinithalassobacter and showed the highest similarity to Sphingosinithalassobacter portus FM6T (97.93 %). Growth occurs at temperatures from 16 to 45 °C (optimum, 30 °C), at pH values between pH 6.0 and 8.5 (optimum, pH 7.0) and in 0–5.0 % (w/v) NaCl (optimum, 1.5 %). The major fatty acids were C16 : 0, C14 : 0 2-OH and summed feature 8 (C18 : 1ω7c and/or C18 : 1ω6c). The major isoprenoid quinone was ubiquinone-10. Predominant polar lipids were diphosphatidylglycerol, phosphatidylglycerol, one unidentified phosphoglycolipid, three unidentified glycolipids and three unidentified phospholipids. The G+C content of the genomic DNA was 64.69 %. The average nucleotide identity values between zrk23T and the most closely related available genome, of Sphingosinithalassobacter portus FM6T, was 82.21 %, indicating that zrk23T was clearly distinguished from S. portus . The analysis of genome sequence of zrk23T revealed that there were many genes associated with degradation of aromatic compounds existing in the genome of zrk23T. As a result of the combination of the results of phylogenetic analysis and phenotypic and chemotaxonomic data, zrk23T was considered to represent a novel species of the genus Sphingosinithalassobacter , for which the name Sphingosinithalassobacter tenebrarum sp. nov. is proposed. The type strain is zrk23T (=KCTC 72896T=MCCC 1K04416T).

Desulfothermus okinawensis sp. nov., a thermophilic and heterotrophic sulfate-reducing bacterium isolated from a deep-sea hydrothermal field

2007 ◽  
Vol 57 (10) ◽  
pp. 2360-2364 ◽  
Author(s):  
Takuro Nunoura ◽  
Hanako Oida ◽  
Masayuki Miyazaki ◽  
Yohey Suzuki ◽  
Ken Takai ◽  
...  
Keyword(s):  
Deep Sea ◽  
Gene Sequence ◽  
Okinawa Trough ◽  
Hydrothermal Field ◽  
Rrna Gene ◽  
Sulfate Reducing ◽  
Gene Sequence Analysis ◽  
Optimum Ph ◽  
Bacterium Strain ◽  
The 16S Rrna Gene

A novel thermophilic and heterotrophic sulfate-reducing bacterium, strain TFISO9T, was isolated from a deep-sea hydrothermal field at the Yonaguni Knoll IV in the Southern Okinawa Trough. The cells were motile rods 2.5–5.0 μm in length and 0.6–0.9 μm in width. Strain TFISO9T was an obligate heterotroph and reduced sulfate. It grew between 35 and 60 °C (optimum 50 °C), at pH 5.4–7.9 (optimum pH 5.9–6.4) and with 1.5–4.5 % NaCl (optimum 2.5 %). The fatty acid composition was C16 : 0 (61.5 %) and 12Me16 : 0 (38.5 %). The DNA G+C content was 34.9 mol%. The 16S rRNA gene sequence analysis indicated that strain TFISO9T belonged to the genus Desulfothermus. Based on physiological and phylogenetic characteristics, strain TFISO9T represents a novel species for which the name Desulfothermus okinawensis sp. nov. is proposed. The type strain is TFISO9T (=JCM 13304T=DSM 17375T).

scholarly journals Psychroserpens Luteus Sp. Nov., Isolated fFrom Red Algae

2021 ◽  
Author(s):  
Xiu-Ya Ping ◽  
Kai Wang ◽  
Jin-Yu Zhang ◽  
Shu-Xin Wang ◽  
Zong-Jun Du ◽  
...  
Keyword(s):  
Red Algae ◽  
Genomic Dna ◽  
Type Strain ◽  
Novel Species ◽  
Sequence Similarity ◽  
Rrna Gene ◽  
Gram Stain ◽  
Optimum Ph ◽  
The 16S Rrna Gene

Abstract A Gram-stain-negative, gliding-motile, positive for catalase, facultative anaerobic, designated strain XSD401T, was isolated from the red algae of Xiaoshi Island, Shandong Province, China. Growth occurred at 20–37 °C (optimum, 33 °C), pH 5.5–9.5 (optimum, pH 6.5–7.5), and with 0.5–5% (w/v) NaCl (optimum, 3%). The main fatty acids are iso-C15:0, iso-C15:1 G, iso-C17:0 3-OH, iso-C15:0 3-OH, C16:0. Phosphatidylethanolamine (PE), three unidentified aminolipids (AL1, AL2, AL3) and one unidentified lipid (L) were the major polar lipids. The G+C content of the genomic DNA was 33.9 mol%. Strain XSD401T had the highest sequence similarity (96.88%) to the 16S rRNA gene of Psychroserpens damuponensis KCTC 23539T. The similarities with Psychroserpens burtonensis DSM 12212T was 96.31%. The dDDH values between strain XSD401T and P. damuponensis KCTC 23539T, P. burtonensis DSM 12212T, were 20.40% and 20.30%, respectively. The average nucleotide identity (ANI) values between strain XSD401T and P. damuponensis KCTC 23539T, P. burtonensis DSM 12212T were 76.91%, 76.88%, respectively. The differences in morphology, physiology and genotype from the previously described taxa support the classification of strain XSD401T as a representative of a novel species of the genus Psychroserpens, for which the name Psychroserpens luteus sp. nov. is proposed. The type strain is XSD401T (= MCCC 1H00396T = KCTC 72684T = JCM 33931T).

scholarly journals Cellulomonas endophytica sp. nov., isolated from Gastrodia elata Blume

2020 ◽  
Vol 70 (5) ◽  
pp. 3091-3095 ◽  
Author(s):  
Yan-Qiong Li ◽  
Hui Zhang ◽  
Min Xiao ◽  
Zhou-Yan Dong ◽  
Jing-Yi Zhang ◽  
...  
Keyword(s):  
Cell Wall ◽  
Type Strain ◽  
Rrna Gene ◽  
Gastrodia Elata ◽  
Content Type ◽  
Link Type ◽  
Optimum Ph ◽  
Pr China ◽  
Phosphatidylinositol Mannosides ◽  
The 16S Rrna Gene

A Gram-stain-positive, facultatively anaerobic and non-motile strain, designated SYSUP0004T, was isolated from the tubers of Gastrodia elata Blume collected from Yunnan Province, PR China. The 16S rRNA gene sequence result showed that the strain SYSUP0004T shared low similarity (97.7 %) with the type strain of Cellulomonas marina . SYSUP0004T grew at pH 6.0–9.0 (optimum, pH 8.0), temperature 4–30 °C (optimum, 28 °C) and could tolerate NaCl up to 4 % w/v (optimum in the absence of NaCl). The cell-wall peptidoglycan type was A4β with an interpeptide bridge l-ornithine–d-glutamic acid. Cell-wall sugars were mannose, ribose, glucose, galactose and fucose. The menaquinone was MK-9(H4). The major fatty acids were anteiso-C15:0, anteiso-C15 : 1 A, C16 : 0 and anteiso-C17 : 0. The polar lipids of SYSUP0004T were diphosphatidylglycerol, unidentified phosphoglycolipid, phosphatidylinositol mannosides and unidentified glycolipid. The genomic DNA G+C content was 76.5 %. The average nucleotide identity values between SYSUP0004T and members of the genus Cellulomonas were below the cut-off level (95–96 %) recommended as the ANI criterion for interspecies identity. Thus, based on the above results strain SYSUP0004T represents a novel species of the genus Cellulomonas , for which the name Cellulomonas endophytica sp. nov. is proposed. The type strain, SYSUP0004T (=KCTC 49025T=CGMCC 1.16405T).

scholarly journals Nautilia nitratireducens sp. nov., a thermophilic, anaerobic, chemosynthetic, nitrate-ammonifying bacterium isolated from a deep-sea hydrothermal vent

2010 ◽  
Vol 60 (5) ◽  
pp. 1182-1186 ◽  
Author(s):  
Ileana Pérez-Rodríguez ◽  
Jessica Ricci ◽  
James W. Voordeckers ◽  
Valentin Starovoytov ◽  
Costantino Vetriani
Keyword(s):  
Gas Phase ◽  
Deep Sea ◽  
Hydrothermal Vent ◽  
Gene Sequence ◽  
Novel Species ◽  
Rrna Gene ◽  
East Pacific ◽  
Optimum Ph ◽  
Casamino Acids ◽  
The 16S Rrna Gene

A thermophilic, anaerobic, chemosynthetic bacterium, designated strain MB-1T, was isolated from the walls of an active deep-sea hydrothermal vent chimney on the East Pacific Rise at  ° 50′ N 10 ° 17′ W. The cells were Gram-negative-staining rods, approximately 1–1.5 μm long and 0.3–0.5 μm wide. Strain MB-1T grew at 25–65 °C (optimum 55 °C), with 10–35 g NaCl l−1 (optimum 20 g l−1) and at pH 4.5–8.5 (optimum pH 7.0). Generation time under optimal conditions was 45.6 min. Growth occurred under chemolithoautotrophic conditions with H2 as the energy source and CO2 as the carbon source. Nitrate was used as the electron acceptor, with resulting production of ammonium. Thiosulfate, sulfur and selenate were also used as electron acceptors. No growth was observed in the presence of lactate, peptone or tryptone. Chemo-organotrophic growth occurred in the presence of acetate, formate, Casamino acids, sucrose, galactose and yeast extract under a N2/CO2 gas phase. The G+C content of the genomic DNA was 36.0 mol%. Phylogenetic analysis of the 16S rRNA gene sequence indicated that this organism is closely related to Nautilia profundicola AmHT, Nautilia abyssi PH1209T and Nautilia lithotrophica 525T (95, 94 and 93 % sequence identity, respectively). On the basis of phylogenetic, physiological and genetic considerations, it is proposed that the organism represents a novel species within the genus Nautilia, Nautilia nitratireducens sp. nov. The type strain is MB-1T (=DSM 22087T =JCM 15746T).

scholarly journals Marinithermofilum abyssi gen. nov., sp. nov. and Desmospora profundinema sp. nov., isolated from a deep-sea sediment, and emended description of the genus Desmospora Yassin et al. 2009

2015 ◽  
Vol 65 (Pt_8) ◽  
pp. 2622-2629 ◽  
Author(s):  
Yi Zhang ◽  
Jie Li ◽  
Xinpeng Tian ◽  
Si Zhang
Keyword(s):  
Fatty Acids ◽  
Deep Sea ◽  
Type Strain ◽  
Novel Species ◽  
Polar Lipids ◽  
Diaminopimelic Acid ◽  
Rrna Gene ◽  
Deep Sea Sediment ◽  
The Family ◽  
Diamino Acid

Two novel filamentous bacteria, strains SCSIO 11157T and SCSIO 11154T, were isolated from a deep-sea sediment sample. Strain SCSIO 11157T grew optimally at 55–60 °C, while strain SCSIO 11154T grew optimally at 40 °C. Both strains produced aerial and substrate mycelia. Phylogenetic analysis of the 16S rRNA gene sequences of strains SCSIO 11157T and SCSIO 11154T showed that the isolates were affiliated to the family Thermoactinomycetaceae. The two isolates contained ll-diaminopimelic acid as the cell-wall diamino acid, and did not have diagnostic sugars. The major polar lipids of strain SCSIO 11157T were diphosphatidylglycerol, phosphatidylmethylethanolamine, phosphatidylethanolamine and phosphatidylglycerol, and the major polar lipids of SCSIO 11154T were diphosphatidylglycerol, phosphatidylglycerol and phosphatidylethanolamine. The predominant menaquinone of both strains was MK-7. The major cellular fatty acids of strain SCSIO 11157T were iso-C15 : 0, C18 : 1ω9c and iso-C17 : 0, and strain SCSIO 11154T contained iso-C15 : 0 and iso-C17 : 0 as major fatty acids. The DNA G+C contents of strains SCSIO 11157T and SCSIO 11154T were 54.2 and 51.8 mol %, respectively. On the basis of its phenotypic and phylogenetic properties, strain SCSIO 11157T represents a novel species in the new genus, for which we propose the name Marinithermofilum abyssi gen. nov., sp. nov. The type strain of Marinithermofilum abyssi is SCSIO 11157T ( = CGMCC 1.15179T = NBRC 109939T). Strain SCSIO 11154T represents a novel species of the genus Desmospora, for which we propose the name Desmospora profundinema sp. nov. The type strain is SCSIO 11154T ( = DSM 45903T = NBRC 109626T).

scholarly journals Marinobacterium lutimaris sp. nov., isolated from a tidal flat

2010 ◽  
Vol 60 (8) ◽  
pp. 1828-1831 ◽  
Author(s):  
Jeong Myeong Kim ◽  
Se Hee Lee ◽  
Ji Young Jung ◽  
Che Ok Jeon
Keyword(s):  
Tidal Flat ◽  
Type Strain ◽  
Novel Species ◽  
Halophilic Bacterium ◽  
Molecular Data ◽  
Rrna Gene ◽  
16S Rrna Gene Sequences ◽  
Gram Staining ◽  
Moderately Halophilic Bacterium ◽  
Optimum Ph

A Gram-staining-negative, moderately halophilic bacterium, designated strain AN9T, was isolated from a tidal flat of the Taean coast in South Korea. Cells were catalase- and oxidase-positive short rods that were motile by means of a single polar flagellum. Growth of strain AN9T was observed at 15–40 °C (optimum, 25–30 °C) and at pH 6.0–8.0 (optimum, pH 6.5–7.5). Strain AN9T contained ubiquinone Q-8 as the predominant isoprenoid quinone and C10 : 0 3-OH (31.7 %), C18 : 1 ω7c (24.8 %), C16 : 0 (14.7 %) and summed feature 3 (comprising C16 : 1 ω7c and/or iso-C15 : 0 2-OH, 10.72 %) as the major fatty acids. The G+C content of the genomic DNA of strain AN9T was 58 mol%. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain AN9T was related to members of the genus Marinobacterium and was related most closely to Marinobacterium litorale IMCC1877T (96.8 % similarity). On the basis of chemotaxonomic and molecular data, strain AN9T is considered to represent a novel species of the genus Marinobacterium, for which the name Marinobacterium lutimaris sp. nov. is proposed. The type strain is AN9T (=KACC 13703T =DSM 22012T).

scholarly journals Genomic and Phylogenetic Characterization of Luminous Bacteria Symbiotic with the Deep-Sea Fish Chlorophthalmus albatrossis (Aulopiformes: Chlorophthalmidae)

2005 ◽  
Vol 71 (2) ◽  
pp. 930-939 ◽  
Author(s):  
Paul V. Dunlap ◽  
Jennifer C. Ast
Keyword(s):  
Deep Sea ◽  
Type Strain ◽  
Photobacterium Phosphoreum ◽  
Phenotypic Traits ◽  
Rrna Gene ◽  
Genomic Profiling ◽  
Light Organ ◽  
Phylogenetic Characterization ◽  
Luminous Bacteria ◽  
High Level

ABSTRACT Bacteria forming light-organ symbiosis with deep-sea chlorophthalmid fishes (Aulopiformes: Chlorophthalmidae) are considered to belong to the species Photobacterium phosphoreum. The identification of these bacteria as P. phosphoreum, however, was based exclusively on phenotypic traits, which may not discriminate between phenetically similar but evolutionarily distinct luminous bacteria. Therefore, to test the species identification of chlorophthalmid symbionts, we carried out a genomotypic (repetitive element palindromic PCR genomic profiling) and phylogenetic analysis on strains isolated from the perirectal light organ of Chlorophthalmus albatrossis. Sequence analysis of the 16S rRNA gene of 10 strains from 5 fish specimens placed these bacteria in a cluster related to but phylogenetically distinct from the type strain of P. phosphoreum, ATCC 11040T, and the type strain of Photobacterium iliopiscarium, ATCC 51760T. Analysis of gyrB resolved the C. albatrossis strains as a strongly supported clade distinct from P. phosphoreum and P. iliopiscarium. Genomic profiling of 109 strains from the 5 C. albatrossis specimens revealed a high level of similarity among strains but allowed identification of genomotypically different types from each fish. Representatives of each type were then analyzed phylogenetically, using sequence of the luxABFE genes. As with gyrB, analysis of luxABFE resolved the C. albatrossis strains as a robustly supported clade distinct from P. phosphoreum. Furthermore, other strains of luminous bacteria reported as P. phosphoreum, i.e., NCIMB 844, from the skin of Merluccius capensis (Merlucciidae), NZ-11D, from the light organ of Nezumia aequalis (Macrouridae), and pjapo.1.1, from the light organ of Physiculus japonicus (Moridae), grouped phylogenetically by gyrB and luxABFE with the C. albatrossis strains, not with ATCC 11040T. These results demonstrate that luminous bacteria symbiotic with C. albatrossis, together with certain other strains of luminous bacteria, form a clade, designated the kishitanii clade, that is related to but evolutionarily distinct from P. phosphoreum. Members of the kishitanii clade may constitute the major or sole bioluminescent symbiont of several families of deep-sea luminous fishes.

scholarly journals Detection of Putatively Thermophilic Anaerobic Methanotrophs in Diffuse Hydrothermal Vent Fluids

2012 ◽  
Vol 79 (3) ◽  
pp. 915-923 ◽  
Author(s):  
Alexander Y. Merkel ◽  
Julie A. Huber ◽  
Nikolay A. Chernyh ◽  
Elizaveta A. Bonch-Osmolovskaya ◽  
Alexander V. Lebedinsky
Keyword(s):  
16S Rrna ◽  
Deep Sea ◽  
Hydrothermal Vents ◽  
Optimal Growth ◽  
16S Rrna Genes ◽  
Rrna Genes ◽  
Rrna Gene ◽  
Anaerobic Oxidation Of Methane ◽  
Phylogenetic Groups ◽  
Content Type

ABSTRACTThe anaerobic oxidation of methane (AOM) is carried out by a globally distributed group of uncultivatedEuryarchaeota, the anaerobic methanotrophic arachaea (ANME). In this work, we used G+C analysis of 16S rRNA genes to identify a putatively thermophilic ANME group and applied newly designed primers to study its distribution in low-temperature diffuse vent fluids from deep-sea hydrothermal vents. We found that the G+C content of the 16S rRNA genes (PGC) is significantly higher in the ANME-1GBa group than in other ANME groups. Based on the positive correlation between thePGCand optimal growth temperatures (Topt) of archaea, we hypothesize that the ANME-1GBa group is adapted to thrive at high temperatures. We designed specific 16S rRNA gene-targeted primers for the ANME-1 cluster to detect all phylogenetic groups within this cluster, including the deeply branching ANME-1GBa group. The primers were successfully tested bothin silicoand in experiments with sediment samples where ANME-1 phylotypes had previously been detected. The primers were further used to screen for the ANME-1 microorganisms in diffuse vent fluid samples from deep-sea hydrothermal vents in the Pacific Ocean, and sequences belonging to the ANME-1 cluster were detected in four individual vents. Phylotypes belonging to the ANME-1GBa group dominated in clone libraries from three of these vents. Our findings provide evidence of existence of a putatively extremely thermophilic group of methanotrophic archaea that occur in geographically and geologically distinct marine hydrothermal habitats.

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