scholarly journals Desulfotomaculum carboxydivorans sp. nov., a novel sulfate-reducing bacterium capable of growth at 100 % CO

2005 ◽  
Vol 55 (5) ◽  
pp. 2159-2165 ◽  
Author(s):  
Sofiya N. Parshina ◽  
Jan Sipma ◽  
Yutaka Nakashimada ◽  
Anne Meint Henstra ◽  
Hauke Smidt ◽  
...  
Keyword(s):  
Gas Phase ◽  
Paper Mill ◽  
Rrna Gene ◽  
Moderately Thermophilic ◽  
Sulfate Reducing ◽  
Nacl Concentration ◽  
Bacterium Strain ◽  
Ph Range ◽  
Desulfotomaculum Nigrificans ◽  
Paper Mill Wastewater

A moderately thermophilic, anaerobic, chemolithoheterotrophic, sulfate-reducing bacterium, strain CO-1-SRBT, was isolated from sludge from an anaerobic bioreactor treating paper mill wastewater. Cells were Gram-positive, motile, spore-forming rods. The temperature range for growth was 30–68 °C, with an optimum at 55 °C. The NaCl concentration range for growth was 0–17 g l−1; there was no change in growth rate until the NaCl concentration reached 8 g l−1. The pH range for growth was 6·0–8·0, with an optimum of 6·8–7·2. The bacterium could grow with 100 % CO in the gas phase. With sulfate, CO was converted to H2 and CO2 and part of the H2 was used for sulfate reduction; without sulfate, CO was completely converted to H2 and CO2. With sulfate, strain CO-1-SRBT utilized H2/CO2, pyruvate, glucose, fructose, maltose, lactate, serine, alanine, ethanol and glycerol. The strain fermented pyruvate, lactate, glucose and fructose. Yeast extract was necessary for growth. Sulfate, thiosulfate and sulfite were used as electron acceptors, whereas elemental sulfur and nitrate were not. A phylogenetic analysis of 16S rRNA gene sequences placed strain CO-1-SRBT in the genus Desulfotomaculum, closely resembling Desulfotomaculum nigrificans DSM 574T and Desulfotomaculum sp. RHT-3 (99 and 100 % similarity, respectively). However, the latter strains were completely inhibited above 20 and 50 % CO in the gas phase, respectively, and were unable to ferment CO, lactate or glucose in the absence of sulfate. DNA–DNA hybridization of strain CO-1-SRBT with D. nigrificans and Desulfotomaculum sp. RHT-3 showed 53 and 60 % relatedness, respectively. On the basis of phylogenetic and physiological features, it is suggested that strain CO-1-SRBT represents a novel species within the genus Desulfotomaculum, for which the name Desulfotomaculum carboxydivorans is proposed. This is the first description of a sulfate-reducing micro-organism that is capable of growth under an atmosphere of pure CO with and without sulfate. The type strain is CO-1-SRBT (=DSM 14880T=VKM B-2319T).

Thermodesulfatator indicus gen. nov., sp. nov., a novel thermophilic chemolithoautotrophic sulfate-reducing bacterium isolated from the Central Indian Ridge

2004 ◽  
Vol 54 (1) ◽  
pp. 227-233 ◽  
Author(s):  
H. Moussard ◽  
S. L'Haridon ◽  
B. J. Tindall ◽  
A. Banta ◽  
P. Schumann ◽  
...  
Keyword(s):  
Type Species ◽  
Phylogenetic Analyses ◽  
Rrna Gene ◽  
Central Indian Ridge ◽  
Sulfate Reducing ◽  
The Family ◽  
Fermentative Growth ◽  
Bacterium Strain ◽  
Indian Ridge ◽  
Ph Range

A thermophilic, marine, anaerobic, chemolithoautotrophic, sulfate-reducing bacterium, strain CIR29812T, was isolated from a deep-sea hydrothermal vent site at the Kairei vent field on the Central Indian Ridge. Cells were Gram-negative motile rods that did not form spores. The temperature range for growth was 55–80 °C, with an optimum at 70 °C. The NaCl concentration range for growth was 10–35 g l−1, with an optimum at 25 g l−1. The pH range for growth was 6–6·7, with an optimum at approximately pH 6·25. H2 and CO2 were the only electron donor and carbon source found to support growth of the strain. However, several organic compounds were stimulatory for growth. Sulfate was used as electron acceptor, whereas elemental sulfur, thiosulfate, sulfite, cystine, nitrate and fumarate were not. No fermentative growth was observed with malate, pyruvate or lactate. The phenotypic characteristics of strain CIR29812T were similar to those of Thermodesulfobacterium hydrogeniphilum, a recently described thermophilic, chemolithoautotrophic sulfate-reducer. However, phylogenetic analyses of the 16S rRNA gene sequences showed that the new isolate was distantly related to members of the family Thermodesulfobacteriaceae (similarity values of less than 90 %). The chemotaxonomic data (fatty acids and polar lipids composition) also indicated that strain CIR29812T could be distinguished from Thermodesulfobacterium commune, the type species of the type genus of the family Thermodesulfobacteriaceae. Finally, the G+C content of the genomic DNA of strain CIR29812T (46·0 mol%) was not in the range of values obtained for members of this family. On the basis of phenotypic, chemotaxonomic and genomic features, it is proposed that strain CIR29812T represents a novel species of a new genus, Thermodesulfatator, of which Thermodesulfatator indicus is the type species. The type strain is CIR29812T (=DSM 15286T=JCM 11887T).

Georgenia sediminis sp. nov., a moderately thermophilic actinobacterium isolated from sediment

2013 ◽  
Vol 63 (Pt_11) ◽  
pp. 4243-4247 ◽  
Author(s):  
Zhi-Qing You ◽  
Jie Li ◽  
Sheng Qin ◽  
Xin-Peng Tian ◽  
Fa-Zuo Wang ◽  
...  
Keyword(s):  
Type Species ◽  
Minor Component ◽  
Optimal Growth ◽  
Rrna Gene ◽  
Content Type ◽  
Moderately Thermophilic ◽  
Link Type ◽  
Nacl Concentration ◽  
Ph Range ◽  
A Minor

A Gram-stain-positive actinobacterium, designated strain SCSIO 15020T, was isolated from sediment of the South China Sea, and characterized by using a polyphasic approach. The temperature range for growth was 24–60 °C, with optimal growth occurring at 50 °C. The pH range for growth was 6–10 (optimum pH 8–9). The NaCl concentration range for growth was 0–5 % (w/v). The peptidoglycan type was A4α. Polar lipids contained diphosphatidylglycerol, phosphatidylglycerol, phosphatidylinositol, phosphatidylinositol mannoside and an unknown polar lipid. The major menaquinone was MK-8(H4); MK-7(H4) was present as a minor component. The major fatty acids (>5 %) were anteiso-C15 : 0, iso-C15 : 0 and iso-C16 : 0. The DNA G+C content of strain SCSIO 15020T was 73.2 mol%. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain SCSIO 15020T belonged to the genus Georgenia , with the closest neighbours being Georgenia muralis 1A-CT (96.3 % similarity), Georgenia thermotolerans TT02-04T (95.7 %) and Georgenia ruanii YIM 004T (95.6 %). Based on evidence from the present polyphasic study, strain SCSIO 15020T is considered to represent a novel species of the genus Georgenia , for which the name Georgenia sediminis sp. nov. is proposed. The type strain is SCSIO 15020T ( = DSM 25884T = NBRC 108941T).

scholarly journals Tepidimicrobium ferriphilum gen. nov., sp. nov., a novel moderately thermophilic, Fe(III)-reducing bacterium of the order Clostridiales

2006 ◽  
Vol 56 (2) ◽  
pp. 369-372 ◽  
Author(s):  
A. I. Slobodkin ◽  
T. P. Tourova ◽  
N. A. Kostrikina ◽  
A. M. Lysenko ◽  
K. E. German ◽  
...  
Keyword(s):  
Hot Spring ◽  
Phylogenetic Analyses ◽  
Casein Hydrolysate ◽  
Rrna Gene ◽  
Donor Strain ◽  
Moderately Thermophilic ◽  
Physiological Properties ◽  
Bacterium Strain ◽  
Casamino Acids ◽  
Ph Range

A moderately thermophilic, anaerobic bacterium (strain SB91T) was isolated from a freshwater hot spring at Barguzin Valley, Buryatiya, Russia. Cells of strain SB91T were straight to slightly curved rods, 0·5–0·6 μm in diameter and 3·0–7·0 μm in length. Formation of endospores was not observed. The temperature range for growth was 26–62 °C, with an optimum at 50 °C. The pH range for growth was 5·5–9·5, with an optimum at pH 7·5–8·0. The substrates utilized by strain SB91T in the presence of 9,10-anthraquinone 2,6-disulfonate included peptone, tryptone, Casamino acids, yeast extract, beef extract, casein hydrolysate, alanine plus glycine, alanine plus proline, l-valine and n-propanol. Carbohydrates were not utilized. Strain SB91T reduced amorphous Fe(III) oxide, Fe(III) citrate, Fe(III) EDTA or Fe(III) nitrilotriacetate with peptone, l-valine or n-propanol as an electron donor. Strain SB91T reduced 9,10-anthraquinone 2,6-disulfonate, thiosulfate, elemental sulfur, fumarate and selenite. Strain SB91T survived after exposure to gamma-radiation at a dose of 5·4 kGy. The G+C content of the DNA of strain SB91T was 33 mol%. Analysis of the 16S rRNA gene sequence revealed that the isolated organism belonged to cluster XII of the clostridia. On the basis of its physiological properties and the results of phylogenetic analyses, it is proposed that strain SB91T represents the sole species of a novel genus, Tepidimicrobium; the name Tepidimicrobium ferriphilum gen. nov., sp. nov. is proposed, with strain SB91T (=DSM 16624T=VKM B-2348T) as the type strain.

scholarly journals Sulfuriferula multivorans gen. nov., sp. nov., isolated from a freshwater lake, reclassification of ‘Thiobacillus plumbophilus’ as Sulfuriferula plumbophilus sp. nov., and description of Sulfuricellaceae fam. nov. and Sulfuricellales ord. nov.

2015 ◽  
Vol 65 (Pt_5) ◽  
pp. 1504-1508 ◽  
Author(s):  
Tomohiro Watanabe ◽  
Hisaya Kojima ◽  
Manabu Fukui
Keyword(s):  
Type Strain ◽  
Sequence Similarity ◽  
Freshwater Lake ◽  
Rrna Gene ◽  
Organic Substrates ◽  
Phenotypic Properties ◽  
Content Type ◽  
Nacl Concentration ◽  
Bacterium Strain ◽  
Ph Range

A sulfur-oxidizing bacterium, strain TTNT, was isolated from a Thioploca sample obtained from a freshwater lake in Japan. The isolate shared 97.1 % 16S rRNA gene sequence similarity with an obligately aerobic chemolithoautotroph, ‘Thiobacillus plumbophilus’ Gro7T. Cells were rods, motile, and Gram-stain-negative. The G+C content of the genomic DNA was approximately 66 mol%. Strain TTNT grew over a temperature range of 8–32 °C (optimum 22–25 °C), an NaCl concentration range of 0–133.3 mM (optimum 0–3.3 mM) and a pH range of 5.3–8.6 (optimum pH 6.4–7.0). Strain TTNT was facultatively anaerobic and could utilize nitrate as an electron acceptor. The isolate oxidized tetrathionate, thiosulfate and elemental sulfur as the sole energy sources for autotrophic growth, and could also grow heterotrophically on a number of organic substrates. Based on its phylogenetic and phenotypic properties, strain TTNT represents a novel species of a novel genus, for which the name Sulfuriferula multivorans gen. nov., sp. nov. is proposed. The type strain is TTNT ( = NBRC 110683T = DSM 29343T). Along with this, the reclassification of ‘Thiobacillus plumbophilus’ as Sulfuriferula plumbophilus sp. nov. (type strain Gro7T = NBRC 107929T = DSM 6690T) is proposed. Based on the data obtained in this study, we describe the designations Sulfuricellaceae fam. nov. and Sulfuricellales ord. nov.

Rhodoligotrophos appendicifer gen. nov., sp. nov., an appendaged bacterium isolated from a freshwater Antarctic lake

2012 ◽  
Vol 62 (Pt_8) ◽  
pp. 1945-1950 ◽  
Author(s):  
Wakao Fukuda ◽  
Kozo Yamada ◽  
Yuki Miyoshi ◽  
Hirokazu Okuno ◽  
Haruyuki Atomi ◽  
...  
Keyword(s):  
New Genus ◽  
Rrna Gene ◽  
16S Rrna Gene Sequences ◽  
Antarctic Lake ◽  
Content Type ◽  
Link Type ◽  
Novel Bacterium ◽  
Nacl Concentration ◽  
Bacterium Strain ◽  
Ph Range

A Gram-stain-negative, non-spore-forming, non-motile, irregularly circular, aerobic/microaerobic appendaged bacterium (strain 120-1T) was isolated from Naga-ike, one of the freshwater lakes in the Skarvsnes ice-free area of Antarctica. Strain 120-1T grew between 5 and 35 °C, with optimum growth at 30 °C. The pH range for growth was between 6.0 and 9.0 (optimum of approximately pH 7.0). The range of NaCl concentration allowing growth of strain 120-1T was between 0 and 5.0 %, with an optimum of 0.5–1.0 %. Strain 120-1T was able to utilize organic compounds such as glucose, arabinose, gluconate, adipate and malate. Red colonies were formed on plate medium and the carotenoids were present in the cells. Ubiquinones Q-9 and Q-10 were the major respiratory quinones. The major cellular fatty acids were C16 : 0, C18 : 1ω9c and C18 : 1ω7c. The G+C content of the genomic DNA was 61.1 mol%. Comparative analyses of 16S rRNA gene sequences and physiological characteristics of strain 120-1T indicate that strain 120-1T is a phylogenetically novel bacterium, and that it represents a novel species in a new genus, Rhodoligotrophos gen. nov., in the order Rhizobiales , family Rhodobiaceae . The name Rhodoligotrophos appendicifer gen. nov. sp. nov. is proposed as the type species of this new genus, with 120-1T ( = JCM 16873T = ATCC BAA-2115T) as the type strain.

scholarly journals Pseudodesulfovibrio Alkaliphilus, Sp. Nov., An Alkaliphilic Sulfate-Reducing Bacterium Isolated From a Terrestrial Mud Volcano

2021 ◽  
Author(s):  
Anastasia Frolova ◽  
Alexander Y. Merkel ◽  
Alexandra A. Kuchierskaya ◽  
Elizaveta A. Bonch-Osmolovskaya ◽  
Alexander I. Slobodkin
Keyword(s):  
Major Product ◽  
Mud Volcano ◽  
Total Size ◽  
Lactate Oxidation ◽  
Sulfate Reducing ◽  
Anaerobic Microorganisms ◽  
Lactate Fermentation ◽  
Bacterium Strain ◽  
Ph Range ◽  
Alkaliphilic Bacterium

Abstract The diversity of anaerobic microorganisms in terrestrial mud volcanoes is largely unexplored. Here we report the isolation of a novel sulfate-reducing alkaliphilic bacterium (strain F-1T) from a terrestrial mud volcano located at the Taman peninsula, Russia. Cells of strain F-1T were Gram- -negative motile vibrios with a single polar flagellum; 2.0–4.0 µm in length and 0.5 µm in diameter. The temperature range for growth was 6–37°C, with an optimum at 24°C. The pH range for growth was 7.0–10.5, with an optimum at pH 9.5. Strain F-1T utilized lactate, pyruvate, and molecular hydrogen as electron donors and sulfate, sulfite, thiosulfate, elemental sulfur, fumarate or arsenate as electron acceptors. In the presence of sulfate the end products of lactate oxidation were acetate, H2S and CO2. Lactate and pyruvate could also be fermented. The major product of lactate fermentation was acetate. The main cellular fatty acids were anteiso-С15:0, С16:0, С18:0, and iso-С17:1ω8. Phylogenetic analysis revealed that strain F-1T was most closely related to Pseudodesulfovibrio aespoeensis (98.05% similarity). The total size of the genome of the novel isolate was 3.23Mb and the genomic DNA G + C content was 61.93 mol%. The genome contained all genes essential for dissimilatoty sulfate reduction. We propose to assign strain F-1T to the genus Pseudodesulfovibrio, as a new species, Pseudodesulfovibrio alkaliphilus sp. nov. The type strain is F-1T (= KCTC 15918T = VKM B-3405T).

scholarly journals Armatimonas rosea gen. nov., sp. nov., of a novel bacterial phylum, Armatimonadetes phyl. nov., formally called the candidate phylum OP10

2011 ◽  
Vol 61 (6) ◽  
pp. 1442-1447 ◽  
Author(s):  
Hideyuki Tamaki ◽  
Yasuhiro Tanaka ◽  
Hiroaki Matsuzawa ◽  
Mizuho Muramatsu ◽  
Xian-Ying Meng ◽  
...  
Keyword(s):  
16S Rrna ◽  
16S Rrna Gene ◽  
Aquatic Plant ◽  
Sequence Similarity ◽  
Limited Range ◽  
Rrna Gene ◽  
16S Rrna Gene Sequences ◽  
Respiratory Quinone ◽  
Bacterium Strain ◽  
Ph Range

A novel aerobic, chemoheterotrophic bacterium, strain YO-36T, isolated from the rhizoplane of an aquatic plant (a reed, Phragmites australis) inhabiting a freshwater lake in Japan, was morphologically, physiologically and phylogenetically characterized. Strain YO-36T was Gram-negative and ovoid to rod-shaped, and formed pinkish hard colonies on agar plates. Strain YO-36T grew at 20–40 °C with optimum growth at 30–35 °C, whilst no growth was observed at 15 °C or 45 °C. The pH range for growth was 5.5–8.5 with an optimum at pH 6.5. Strain YO-36T utilized a limited range of substrates, such as sucrose, gentiobiose, pectin, gellan gum and xanthan gum. The strain contained C16 : 0, C16 : 1, C14 : 0 and C15 : 0 as the major cellular fatty acids and menaquinone-12 as the respiratory quinone. The G+C content of the genomic DNA was 62.4 mol%. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain YO-36T belonged to the candidate phylum OP10 comprised solely of environmental 16S rRNA gene clone sequences except for two strains, P488 and T49 isolated from geothermal soil in New Zealand; strain YO-36T showed less than 80 % sequence similarity to strains P488 and T47. Based on the phylogetic and phenotypic findings, a new genus and species, Armatimonas rosea gen. nov., sp. nov., is proposed for the isolate (type strain YO-36T  = NBRC 105658T  = DSM 23562T). In addition, a new bacterial phylum named Armatimonadetes phyl. nov. is proposed for the candidate phylum OP10 represented by A. rosea gen. nov., sp. nov. and Armatimonadaceae fam. nov., Armatimonadales ord. nov., and Armatimonadia classis nov.

Natranaerobaculum magadiense gen. nov., sp. nov., an anaerobic, alkalithermophilic bacterium from soda lake sediment

2013 ◽  
Vol 63 (Pt_12) ◽  
pp. 4456-4461 ◽  
Author(s):  
Daria G. Zavarzina ◽  
Tatyana N. Zhilina ◽  
Boris B. Kuznetsov ◽  
Tatyana V. Kolganova ◽  
Georgy A. Osipov ◽  
...  
Keyword(s):  
Yeast Extract ◽  
Sequence Similarity ◽  
Soda Lake ◽  
Rrna Gene ◽  
Donor Strain ◽  
Content Type ◽  
Link Type ◽  
Nacl Concentration ◽  
Novel Genus And Species ◽  
Ph Range

An obligately alkaliphilic, anaerobic, thermo- and halotolerant, spore-forming bacterium was isolated from sediments of soda lake Magadi (Kenya) and designated strain Z-1001T. Cells of strain Z-1001T were straight, Gram-positive rods, slowly motile. Strain Z-1001T was found to be an obligate anaerobe. It grew within a pH range from 7.5 to 10.7 with an optimum at 9.25–9.5 (at 40 °C), a temperature range from 20 to 57 °C with an optimum at 45–50 °C, and a NaCl concentration range from 0 to 1.55 M with an optimum at 1.2–1.4 M. Peptides, such as meat and yeast extracts, peptone and tryptone, were fermented by Z-1001T. Carbohydrates did not support growth. With yeast extract as an electron donor, strain Z-1001T reduced S 2 O 3 2 − , NO 3 − , AsO 4 3 − , Fe(III) citrate and anthraquinone-2,6-disulfonate (AQDS) as electron acceptors. The isolate was able to grow oligotrophically with a very small amount of yeast extract: 0.03 g l−1. The main fatty acids were C16 : 0, C16 : 1ω7c , C18 : 0 and C18 : 1ω9. The DNA G+C content of the isolate was 35.6 mol%. 16S rRNA gene sequence analysis showed that strain Z-1001T is a member of family Natranaerobiaceae , clustering with the type strain of Natranaerobius thermophilus (95.8–96.0 % sequence similarity). On the basis of physiological and phylogenetic data it is proposed that strain Z-1001T ( = DSM 24923T = VKM B-2666T) represents a novel genus and species, Natranaerobaculum magadiense gen. nov., sp. nov.

scholarly journals Desulfobulbus japonicus sp. nov., a novel Gram-negative propionate-oxidizing, sulfate-reducing bacterium isolated from an estuarine sediment in Japan

2007 ◽  
Vol 57 (4) ◽  
pp. 849-855 ◽  
Author(s):  
Daisuke Suzuki ◽  
Atsuko Ueki ◽  
Aya Amaishi ◽  
Katsuji Ueki
Keyword(s):  
Estuarine Sediment ◽  
Electron Donors ◽  
The Sea Of Japan ◽  
Rrna Gene ◽  
Strictly Anaerobic ◽  
Bacterial Strains ◽  
Respiratory Quinone ◽  
Gram Negative ◽  
Sulfate Reducing ◽  
Nacl Concentration

Two strictly anaerobic, mesophilic, sulfate-reducing bacterial strains, Pro1T and Pro16, were isolated from an estuarine sediment in the Sea of Japan of the Japanese islands and were characterized by phenotypic and phylogenetic methods. Strains Pro1T and Pro16 had almost the same physiological and chemotaxonomic characteristics. Cells of both strains were Gram-negative, motile, non-spore-forming rods. Catalase activity was not detected. The optimum NaCl concentration for growth was 3.0 % (w/v). The optimum temperature for growth was 35 °C and the optimum pH was 6.7. Both strains used formate, propionate, pyruvate, lactate, fumarate, malate, ethanol, propanol, butanol, glycerol, alanine, glucose, fructose and H2 as electron donors for sulfate reduction and did not use acetate, butyrate, succinate, methanol, glycine, serine, aspartate, glutamate, cellobiose or sucrose. Organic electron donors were incompletely oxidized mainly to acetate. Both strains also used thiosulfate as an electron acceptor. Without electron acceptors, both strains fermented pyruvate and lactate. The genomic DNA G+C contents of strains Pro1T and Pro16 were 48.6 and 46.0 mol%, respectively. The major respiratory quinone of both strains was menaquinone MK-5(H2). Major cellular fatty acids of both strains were C15 : 0, C16 : 0, C17 : 1 ω6 and C18 : 1 ω7. Phylogenetic analysis based on 16S rRNA gene sequences placed both strains in the class Deltaproteobacteria. The closest recognized relative of strains Pro1T and Pro16 was Desulfobulbus mediterraneus with sequence similarities of 95.2 and 94.8 %, respectively. Based on phylogenetic, physiological and chemotaxonomic characteristics, strains Pro1T and Pro16 represent a novel species of the genus Desulfobulbus, for which the name Desulfobulbus japonicus is proposed. The type strain is Pro1T(=JCM 14043T=DSM 18378T) and strain Pro16 (=JCM 14044=DSM 18379) is a reference strain.

scholarly journals Thermococcus thioreducens sp. nov., a novel hyperthermophilic, obligately sulfur-reducing archaeon from a deep-sea hydrothermal vent

2007 ◽  
Vol 57 (7) ◽  
pp. 1612-1618 ◽  
Author(s):  
Elena V. Pikuta ◽  
Damien Marsic ◽  
Takashi Itoh ◽  
Asim K. Bej ◽  
Jane Tang ◽  
...  
Keyword(s):  
Hydrothermal Vent ◽  
Rrna Gene ◽  
Strictly Anaerobic ◽  
Black Smoker ◽  
Separate Species ◽  
Gene Sequence Analysis ◽  
Nacl Concentration ◽  
Mid Atlantic Ridge ◽  
Casamino Acids ◽  
Ph Range

A hyperthermophilic, sulfur-reducing, organo-heterotrophic archaeon, strain OGL-20PT, was isolated from ‘black smoker’ chimney material from the Rainbow hydrothermal vent site on the Mid-Atlantic Ridge (36.2°N, 33.9°W). The cells of strain OGL-20PT have an irregular coccoid shape and are motile with a single flagellum. Growth was observed within a pH range of 5.0−8.5 (optimum pH 7.0), an NaCl concentration range of 1–5 % (w/v) (optimum 3 %) and a temperature range of 55–94 °C (optimum 83–85 °C). The novel isolate is strictly anaerobic and obligately dependent upon elemental sulfur as an electron acceptor, but it does not reduce sulfate, sulfite, thiosulfate, Fe(III) or nitrate. Proteolysis products (peptone, bacto-tryptone, Casamino acids and yeast extract) are utilized as substrates during sulfur reduction. Strain OGL-20PT is resistant to ampicillin, chloramphenicol, kanamycin and gentamicin, but sensitive to tetracycline and rifampicin. The G+C content of the DNA is 52.9 mol%. The 16S rRNA gene sequence analysis revealed that strain OGL-20PT is closely related to Thermococcus coalescens and related species, but no significant homology by DNA–DNA hybridization was observed between those species and the new isolate. On the basis of physiological and molecular properties of the new isolate, we conclude that strain OGL-20PT represents a new separate species within the genus Thermococcus, for which we propose the name Thermococcus thioreducens sp. nov. The type strain is OGL-20PT (=JCM 12859T=DSM 14981T=ATCC BAA-394T).

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