Tepidibacillus fermentans gen. nov., sp. nov.: a moderately thermophilic anaerobic and microaerophilic bacterium from an underground gas storage

A novel moderately thermophilic bacterium, strain STGH(T), was isolated from Severo-Stavropolskoye underground gas storage (Russia). Cells of strain STGH(T) were spore-forming motile straight rods 0.3 μm in diameter and 2.0-4.0 μm in length having a Gram-positive cell wall structure. The temperature range for growth was 36-65 °C, with an optimum at 50-52 °C. The pH range for growth was 5.5-8.0, with an optimum at pH 7.0-7.5. Growth of strain STGH(T) was observed at NaCl concentrations ranging from 0 to 4.0 % (w/v) with an optimum at 1.0 % (w/v). Strain STGH(T) grew anaerobically by reduction of nitrate, thiosulfate, S(0) and AQDS using a number of complex proteinaceous compounds, organic acids and carbohydrates as electron donors. Nitrate was reduced to nitrite; thiosulfate and sulfur were reduced to sulfide. It also was able to ferment pyruvate, glucose, fructose, and maltose. The strain STGH(T) did not grow under aerobic conditions during incubation with atmospheric concentration of oxygen but was able to microaerobic growth (up to 10 % of oxygen in gas phase). The G+C content of DNA of strain STGH(T) was 34.8 mol%. 16S rRNA gene sequence analysis revealed that the isolated organism belongs to the class Bacilli. We propose to assign strain STGH(T) to a new species of a novel genus Tepidibacillus fermentans gen. nov., sp.nov. The type strain is STGH(T) (=DSM 23802(T), =VKM B-2671(T)).

Dissulfuribacter thermophilus gen. nov., sp. nov., a thermophilic, autotrophic, sulfur-disproportionating, deeply branching deltaproteobacterium from a deep-sea hydrothermal vent

A thermophilic, anaerobic, chemolithoautotrophic bacterium (strain S69T) was isolated from a deep-sea hydrothermal vent chimney located on the Eastern Lau Spreading Center and Valu Fa Ridge, Pacific Ocean, at a depth of 1910 m using anoxic medium with elemental sulfur as the only energy source. Cells of strain S69T were Gram-negative short rods, 0.4–0.6 µm in diameter and 1.0–2.5 µm in length, motile with a single polar flagellum. The temperature range for growth was 28–70 °C, with an optimum at 61 °C. The pH range for growth was 5.6–7.9, with optimum growth at pH 6.8. Growth of strain S69T was observed at NaCl concentrations ranging from 0.9 to 5.0 %, with an optimum at 1.8–2.7 (w/v). Strain S69T grew anaerobically with elemental sulfur as an energy source and bicarbonate/CO2 as a carbon source. Elemental sulfur was disproportionated to sulfide and sulfate. Growth was enhanced in the presence of poorly crystalline Fe(III) oxide (ferrihydrite) as a sulfide-scavenging agent. Strain S69T was also able to grow by disproportionation of thiosulfate and sulfite. Sulfate was not used as an electron acceptor either with H2 or with organic electron donors. Analysis of the 16S rRNA gene sequence revealed that the isolate formed a distinct phylogenetic branch within the Deltaproteobacteria . On the basis of its physiological properties and results of phylogenetic analyses, strain S69T is considered to represent a novel species of a new genus, for which the name Dissulfuribacter thermophilus gen. nov., sp. nov. is proposed. The type strain of Dissulfuribacter thermophilus is S69T ( = DSM 25762T = VKM B-2760T).

Thermosulfurimonas dismutans gen. nov., sp. nov., an extremely thermophilic sulfur-disproportionating bacterium from a deep-sea hydrothermal vent

An extremely thermophilic, anaerobic, chemolithoautotrophic bacterium (strain S95(T)) was isolated from a deep-sea hydrothermal vent chimney located on the Eastern Lau Spreading Center, Pacific Ocean, at a depth of 1910 m. Cells of strain S95(T) were oval to short Gram-negative rods, 0.5-0.6 µm in diameter and 1.0-1.5 µm in length, growing singly or in pairs. Cells were motile with a single polar flagellum. The temperature range for growth was 50-92 °C, with an optimum at 74 °C. The pH range for growth was 5.5-8.0, with an optimum at pH 7.0. Growth of strain S95(T) was observed at NaCl concentrations ranging from 1.5 to 3.5% (w/v). Strain S95(T) grew anaerobically with elemental sulfur as an energy source and bicarbonate/CO(2) as a carbon source. Elemental sulfur was disproportionated to sulfide and sulfate. Growth was enhanced in the presence of poorly crystalline iron(III) oxide (ferrihydrite) as a sulfide-scavenging agent. Strain S95(T) was also able to grow by disproportionation of thiosulfate and sulfite. Sulfate was not used as an electron acceptor. Analysis of the 16S rRNA gene sequence revealed that the isolate belongs to the phylum Thermodesulfobacteria. On the basis of its physiological properties and results of phylogenetic analyses, it is proposed that the isolate represents the sole species of a new genus, Thermosulfurimonas dismutans gen. nov., sp. nov.; S95(T) (=DSM 24515(T)=VKM B-2683(T)) is the type strain of the type species. This is the first description of a thermophilic micro-organism that disproportionates elemental sulfur.

Deferrisoma camini gen. nov., sp. nov., a moderately thermophilic, dissimilatory iron(III)-reducing bacterium from a deep-sea hydrothermal vent that forms a distinct phylogenetic branch in the Deltaproteobacteria

A moderately thermophilic, anaerobic, dissimilatory iron(III)-reducing bacterium (strain S3R1(T)) was isolated from a deep-sea hydrothermal vent chimney located on the Eastern Lau Spreading Centre in the Pacific Ocean at a depth of about 2150 m. Cells of strain S3R1(T) were ovals to short rods with a single polar flagellum, Gram-stain-negative, 0.5-0.6 µm in diameter and 0.8-1.3 µm long, growing singly or in pairs. The temperature range for growth was 36-62 °C, with an optimum at 50 °C. The pH range for growth was 5.5-7.5, with an optimum at pH 6.5. Growth of strain S3R1(T) was observed at NaCl concentrations ranging from 1.0 to 5.0 % (w/v), with an optimum at 2.0-2.5 % (w/v). The isolate used acetate, fumarate, malate, maleinate, succinate, propanol, palmitate, stearate, peptone and yeast extract as electron donors for growth and iron(III) reduction. All electron donors were oxidized completely to CO(2) and H(2)O. Iron(III) (in the form of ferrihydrite, ferric citrate or ferric nitrilotriacetate) and elemental sulfur (S(0)) were the electron acceptors that supported growth. The DNA G+C content was 64.4 mol%. Results of 16S rRNA gene sequence analysis showed that the novel bacterium was related to representatives of the orders Desulfuromonadales and Syntrophobacterales with 84-86 % sequence similarity and formed a distinct phylogenetic branch in the Deltaproteobacteria. On the basis of its physiological properties and results of phylogenetic analyses, it is proposed that the new isolate represents the sole species of a novel genus, Deferrisoma camini gen. nov., sp. nov. The type strain of Deferrisoma camini is S3R1(T) ( = DSM 24185(T)  = VKM B-2672(T)).

Caloribacterium cisternae gen. nov., sp. nov., an anaerobic thermophilic bacterium from an underground gas storage reservoir

A novel anaerobic, moderately thermophilic bacterium (strain SGL43(T)) was isolated from Severo-Stavropolskoye underground gas storage reservoir (Russia). Cells of strain SGL43(T) were motile straight rods, 0.4 µm in diameter and 2.0-3.0 µm in length. The temperature range for growth was 28-65 °C, with optimum growth at 50 °C. The pH range for growth was 5.5-8.0, with optimum growth at pH 7.0-7.5. Growth of strain SGL43(T) was observed at NaCl concentrations of 0-4.0% (w/v) with optimum growth at 1.0% (w/v) NaCl. Substrates utilized by strain SGL43(T) included peptone, yeast extract, glucose, fructose, maltose, galactose, pyruvate and citrate. Products of glucose or citrate fermentation were acetate, hydrogen and CO(2). Thiosulfate was reduced to sulfide. The DNA G+C content of strain SGL43(T) was 43.1 mol%. 16S rRNA gene sequence analysis revealed that strain SGL43(T) belongs to the order Thermoanaerobacterales (phylum 'Firmicutes'). The closest relative of strain SGL43(T) was Thermoanaerobacterium saccharolyticum (86.2% 16S rRNA gene sequence similarity with the type strain). Based on the data presented here, strain SGL43(T) is considered to represent a novel species of a new genus, for which the name Caloribacterium cisternae gen. nov., sp. nov. is proposed. The type strain of Caloribacterium cisternae, the type species of the genus, is SGL43(T) (=DSM 23830(T)=VKM B-2670(T)).

Thermoanaerobacterium aciditolerans sp. nov., a moderate thermoacidophile from a Kamchatka hot spring

An anaerobic, moderately thermoacidophilic bacterium, strain 761-119T, was isolated from an acidic hot spring in the Orange Field of the Uzon Caldera (Kamchatka, far-eastern Russia). Cells were spore-forming, Gram-positive rods, possessing one polar flagellum. Growth of strain 761-119Twas observed between 37 and 68 °C and in the pH20 °Crange 3.2–7.1. No growth was observed within 5 days of incubation at or below 35 °C and at or above 70 °C, as well as at or below pH20 °C2.8 and at or above pH20 °C7.5. The optimal temperature and pH20 °Cfor growth were 55 °C and pH20 °C5.7, respectively. A wide range of carbohydrates and polysaccharides were fermented, as well as peptides and proteinaceous substrates. The main products of glucose fermentation were acetate, ethanol, lactate, H2and CO2. The DNA G+C content was 34 (±0.5) mol%. 16S rRNA gene sequence analysis indicated that strain 761-119Tbelonged to the genusThermoanaerobacterium. The level of 16S rRNA gene sequence similarity with otherThermoanaerobacteriumspecies was 86.5–97.8 %, with the only moderately acidophilic member of this genus,Thermoanaerobacterium aotearoense, being one of its closest relatives. DNA–DNA hybridization withT. aotearoenseshowed 33 % relatedness. Thus, morphological (one polar flagellum) and physiological characteristics (lower pH limit of growth at pH20 °C3.2 compared withT. aotearoense) and 16S rRNA gene sequence analyses revealed that strain 761-119Trepresents a novel species in the genusThermoanaerobacterium, for which the nameThermoanaerobacterium aciditoleranssp. nov. is proposed, with the type strain 761-119T(=DSM 16487T=VKM B-2363T).

[Geoalkalibacter ferrihydriticus gen. nov., sp. nov., the first alkaliphilic representative of the family Geobacteraceae, isolated from a soda lake]

Investigation of iron reduction in bottom sediments of alkaline soda lakes resulted in the isolation of a new obligately anaerobic iron-reducing bacterium, strain Z-0531, from Lake Khadyn (Tuva Republic, Russia) sediment samples. The cells of strain Z-0531 are short (1.0-1.5 by 0.3-0.5 microm), motile, non-spore-forming, gram-negative rods. The isolate is an obligate alkaliphile, developing in the pH range of 7.8-10.0, with an optimum at pH 8.6. It does not require NaCl but grows at NaCl concentrations of 0-50 g/1l. It can oxidize acetate with such electron acceptors as amorphous Fe(llI) hydroxide (AFH), EDTA-Fe(III), anthraquinone-2,6-disulfonate (quinone), Mn(IV), and S(0). On media with EDTA-Fe(III), the isolate can oxidize, apart from acetate, ethanol, pyruvate, oxalate, arginine, tartrate, lactate, propionate, and serine. H2 is not utilized. The reduced products formed during growth with AFH are siderite or magnetite, depending on the growth conditions. The isolate is incapable of fermenting sugars, peptides, and amino acids. Yeast extract or vitamins are required as growth factors. The organism is capable of dinitrogen fixation and harbors the nifH gene. The DNA G+C content is 55.3 mol %. 16S rRNA analysis places strain Z-0531 into the family Geobacteraceae. Its closest relative (93% similarity) is Desulfuromonas palmitatis. Based on phenotypic distinctions and phylogenetic position, it is proposed that strain Z-0531 be assigned to the new genus and species Geoalkalibacter ferrihydriticus gen. nov., sp. nov.

Vulcanibacillus modesticaldus gen. nov., sp. nov., a strictly anaerobic, nitrate-reducing bacterium from deep-sea hydrothermal vents

A novel anaerobic, moderately thermophilic, spore-forming bacterium, designated strain BRT, was isolated from deep-sea hydrothermal core samples collected at the Rainbow vent field on the Mid-Atlantic Ridge (36 degrees 14' N 33 degrees 54' W). The cells were found to be rod-shaped, non-motile, Gram-positive and spore-forming. The organism grew in the temperature range 37-60 degrees C, with an optimum at 55 degrees C, and at pH values in the range 6-8.5, with an optimum around pH 7. NaCl concentrations for growth were in the range 10-40 g l(-1), with an optimum at 20-30 g l(-1). Strain BRT grew chemo-organoheterotrophically with carbohydrates, proteinaceous substrates and organic acids with nitrate as electron acceptor. The novel isolate was not able to ferment. The G+C content of the genomic DNA was 34.5 mol%. Phylogenetic analysis of the 16S rRNA gene sequence placed strain BRT in the Bacillaceae within the class 'Bacilli'. On the basis of the phenotypic and phylogenetic data, this isolate should be described as a member of a novel genus, for which the name Vulcanibacillus gen. nov. is proposed. The type species is Vulcanibacillus modesticaldus sp. nov., with the type strain BRT (=DSM 14931T=JCM 12998T).

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

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.

[Clostridium alkalicellum sp. nov., an obligately alkaliphilic cellulolytic bacterium from a soda lake in the Baikal region]

The first anaerobic alkaliphilic cellulolytic microorganism has been isolated from the Verkhnee Beloe soda lake (Buryatiya, Russia) with pH 10.2 and a salt content of up to 24 g/l. Five strains were characterized. Strain Z-7026 was chosen as the type strain. The cells of the isolate are gram-positive spore-forming rods. A mucous external capsule is produced. The microorganism is obligately alkaliphilic, growing in a pH range of 8.0-10.2, with an optimum at pH 9.0. Sodium ions and, in carbonate-buffered media, sodium chloride are obligately required. The microorganism is slightly halophilic; it grows at 0.017-0.4 M Na+ with an optimum at 0.15-0.3 M Na+. The metabolism is fermentative and strictly anaerobic. Cellulose, cellobiose, and xylan can be used as growth substrates. Plant and algal debris can be fermented. Lactate, ethanol, acetate, hydrogen, and traces of formate are produced during cellulose or cellobiose fermentation. Yeast extract or vitamins are required for anabolic purposes. The microorganism fixes dinitrogen and is nitrogenase-positive. It is tolerant to up to 48 mM Na2S. Growth is not inhibited by kanamycin or neomycin. Chloramphenicol, streptomycin, penicillin, ampicillin, ampiox, bacillin, novobiocin, and bacitracin suppress growth. The DNA G+C content is 29.9 mol %. According to the nucleotide sequence of its 16S rRNA gene, strain Z-7026 is phylogenetically close to the neutrophilic cellulolytic bacteria Clostridium thermocellum (95.5%), C. aldrichii (94.9%), and Acetivibrio cellulolyticus (94.8%). It is proposed as a new species: Clostridium alkalicellum sp. nov.

Desulfurococcus fermentans sp. nov., a novel hyperthermophilic archaeon from a Kamchatka hot spring, and emended description of the genus Desulfurococcus

An obligately anaerobic, hyperthermophilic, organoheterotrophic archaeon, strain Z-1312T, was isolated from a freshwater hot spring of the Uzon caldera (Kamchatka Peninsula, Russia). The cells were regular cocci, 1–4 μm in diameter, with one long flagellum. The cell envelope was composed of a globular layer attached to the cytoplasmic membrane. The temperature range for growth was 63–89 °C, with an optimum between 80 and 82 °C. The pH range for growth at 80 °C was 4·8–6·8, with an optimum at pH 6·0. Strain Z-1312Tgrew by hydrolysis and/or fermentation of a wide range of polymeric and monomeric substrates, including agarose, amygdalin, arabinose, arbutin, casein hydrolysate, cellulose (filter paper, microcrystalline cellulose, carboxymethyl cellulose), dextran, dulcitol, fructose, lactose, laminarin, lichenan, maltose, pectin, peptone, ribose, starch and sucrose. No growth was detected on glucose, xylose, mannitol or sorbitol. Growth products when sucrose or starch were used as the substrate were acetate, H2and CO2. Elemental sulfur, thiosulfate and nitrate added as potential electron acceptors for anaerobic respiration did not stimulate growth when tested with starch as the substrate. H2at 100 % in the gas phase did not inhibit growth on starch or peptone. The G+C content of the DNA was 42·5 mol%. 16S rRNA gene sequence analysis placed the isolated strain Z-1312Tas a member of the genusDesulfurococcus, where it represented a novel species, for which the nameDesulfurococcus fermentanssp. nov. (type strain Z-1312T=DSM 16532T=VKM V-2316T) is proposed.

[Detection of a cultivated hyperthermophilic archaeon of the genus Sulfophobococcus in a methane tank operated in a thermophilic regime]

A stable association of hyperthermophilic microorganisms (82 degrees C), which contained mostly cocci and a minor amount of non-spore-forming rods, was obtained from the fermented sludge of a methane tank used to process municipal wastewaters under thermophilic conditions (50 degrees C). PCR amplification of 16S rRNA genes using total DNA isolated from this association and archaea-specific primers, followed by sequencing of the product obtained, showed that the archaeal component was represented by a single nucleotide sequence, which was 99.9% homologous to 16S rRNA gene of Sulfophobococcus zilligii. Thus, a hyperthermophilic archaeon was for the first time detected in a system of anaerobic biological treatment of wastewater. In addition, this is the first report on the detection of a cultivated member of Crenarchaeota in anthropogenic habitats with neutral pH.

[Halomonas campisalis, an obligatorily alkaliphilic, nitrous oxide-reducing denitrifier with a Mo-cofactor-lacking nitrate reductase]

We isolated eight strains of denitrifying bacteria that reduce nitrate and nitrous oxide at pH 10 from Lake Magadi (Kenya). Despite certain differences between the strains, they are similar in terms of G+C content (66.1-68.1 mol %) and DNA-DNA homology (75-92%) and represent different morphotypes of the same species. Based on the results of partial 16S rRNA sequencing, strain Z-7398-2 was most closely related to the Halomonas campisalis isolate from Alkali Lake (USA). The DNA-DNA homology level between the tested strain and the type strain of H. campisalis 4A was 88%. These two strains were also similar phenotypically. However, the culture isolated by us was characterized by peculiar properties, such as obligate alkaliphily, which manifested itself in the culture dependence on carbonates and lack of growth at pH values below 7, a nitrous oxide-reducing capacity, and an unusual nitrate reductase that lacked molybdenum and a Mo cofactor.

Deferribacter abyssi sp. nov., an anaerobic thermophile from deep-sea hydrothermal vents of the Mid-Atlantic Ridge

Two strains of thermophilic, anaerobic, chemolithoautotrophic bacteria, designated JR(T) and DR, were isolated from hydrothermal samples collected on the Mid-Atlantic Ridge from the Rainbow (36 degrees 16' N, 33 degrees 54' W) and Menez Gwen (37 degrees 50' N, 31 degrees 50' W) vent fields, respectively. Cells of both isolates were short, straight- to vibrio-shaped, motile rods with one polar flagellum, and were Gram-negative and non-sporulating. Strain JR(T) was characterized in detail. It was found to grow optimally at pH 6.5-6.7, at 60 degrees C and in the presence of 30 g NaCl l(-1). Strain JR(T) could use molecular hydrogen, acetate, succinate, pyruvate and proteinaceous compounds as electron donors, and elemental sulfur, nitrate or Fe(III) as electron acceptors. No fermentation of organic substrates occurred. The G+C content of the DNA of strain JR(T) was 30.8 mol%. Strain DR (=DSM 14927) possessed the same morphology and pH, temperature and salinity optima and ranges, and used the same electron acceptors as strain JR(T). On the basis of their 16S rDNA sequences (1517 nucleotides), strains JR(T) and DR were identical and distantly related to Deferribacter thermophilus and Deferribacter desulfuricans (95.3 and 95.2 % sequence similarity, respectively). Based on their phenotypic and phylogenetic characteristics, it is proposed that both strains are members of a new species of the genus Deferribacter, for which the name Deferribacter abyssi (type strain JR(T)=DSM 14873(T)=JCM 11955(T)) is proposed.

Vulcanithermus mediatlanticus gen. nov., sp. nov., a novel member of the family Thermaceae from a deep-sea hot vent

A novel thermophilic, microaerophilic, facultatively chemolithoheterotrophic bacterium designated strain TR(T) was isolated from a sample of a deep-sea hydrothermal chimney collected at the Rainbow vent field on the Mid-Atlantic Ridge (36 degrees 14'N). Gram-negative, non-spore-forming, non-motile rods occurred singly or in pairs. The organism grew in the temperature range 37-80 degrees C with an optimum at 70 degrees C and at pH 5.5-8.4 with an optimum around 6.7. The NaCl range for growth was 10-50 g l(-1) with an optimum of 30 g l(-1). Strain TR(T) grew chemoorganoheterotrophically with carbohydrates, proteinaceous substrates, organic acids and alcohols using oxygen or nitrate as electron acceptors. The isolate was able to grow at oxygen concentrations from 0.5 to 21%. Oxygen concentrations that promoted fastest growth ranged from 4 to 8% under agitation. The novel isolate was able to grow lithoheterotrophically with molecular hydrogen as the energy source. The G + C content of the genomic DNA was 68.4 mol%. Phylogenetic analysis of the 16S rDNA sequence placed strain TR(T) within the phylum Deinococcus-Thermus of the Bacteria. On the basis of phenotypic and phylogenetic data, it is proposed that this isolate should be described as a member of a novel species of a new genus as Vulcanithermus mediatlanticus gen. nov., sp. nov. The type strain is TR(T) (= DSM 14978T = VKM B-2292T = JCM 11956T).

Tepidibacter thalassicus gen. nov., sp. nov., a novel moderately thermophilic, anaerobic, fermentative bacterium from a deep-sea hydrothermal vent

A moderately thermophilic, anaerobic, endospore-forming bacterium (strain SC 562T) was isolated from a hydrothermal vent chimney located at 13 degrees N on the East-Pacific Rise at a depth of 2650 m. Cells of strain SC 562T were straight to slightly curved rods, which were 0.7-0.9 microm in diameter and 3.5-6.0 microm in length with peritrichous flagella. Strain SC 562T formed round, refractile endospores in terminally swollen sporangia. The temperature range for growth was 33-60 degrees C, with an optimum at 50 degrees C. The pH range for growth was 4.8-8.5, with an optimum at pH 6.5-6.8. Growth of strain SC 562T was observed at NaCl concentrations ranging from 1.5 to 6% (w/v). The substrates utilized by strain SC 562T included casein, peptone, albumin, yeast extract, beef extract, alanine plus proline and starch. Glucose, maltose, pyruvate, valine and arginine each slightly stimulated growth in the presence of yeast extract. The products of glucose fermentation were ethanol, acetate, H2 and CO2. Strain SC 562T reduced elemental sulfur to hydrogen sulfide. The G + C content of the DNA of strain SC 562T was 24 mol%. 16S rDNA sequence analysis revealed that the isolated organism belonged to cluster XI of the Clostridium subphylum. On the basis of its physiological properties and phylogenetic analyses, it is proposed that strain SC 562T represents the sole species of a novel genus, Tepidibacter; the name Tepidibacter thalassicus is proposed for strain SC 562T (=DSM 15285T=UNIQEM 215T).

Oceanithermus profundus gen. nov., sp. nov., a thermophilic, microaerophilic, facultatively chemolithoheterotrophic bacterium from a deep-sea hydrothermal vent

A novel moderately thermophilic, organotrophic, microaerophilic, facultatively chemolithotrophic bacterium, designated strain 506(T), was isolated from a deep-sea hydrothermal vent site at 13 degrees N in the East Pacific Rise. Cells were Gram-negative, non-motile rods. The organism grew in the temperature range 40-68 degrees C, with an optimum at 60 degrees C, and in the pH range 5.5-8.4, with an optimum around pH 7.5. The NaCl concentration for growth was in the range 10-50 g l(-1), with an optimum at 30 g l(-1). Strain 506(T) grew chemoorganoheterotrophically with carbohydrates, proteinaceous substrates, organic acids and alcohols using oxygen or nitrate as electron acceptor. Alternatively, strain 506(T) was able to grow lithoheterotrophically with molecular hydrogen as the energy source. The G +C content of the genomic DNA was 62.9 mol%. Phylogenetic analysis of the 16S rDNA sequence placed strain 506(T) in the family Thermaceae. On the basis of phenotypic and phylogenetic data, strain 506(T) (= DSM 14977(T) = VKM B-2274(T)) is proposed as the type strain of a novel species in a new genus, Oceanithermus profundus gen. nov., sp. nov.

Carboxydocella thermautotrophica gen. nov., sp. nov., a novel anaerobic, CO-utilizing thermophile from a Kamchatkan hot spring

A novel anaerobic, thermophilic, CO-utilizing bacterium, strain 41(T), was isolated from a terrestrial hot vent on the Kamchatka Peninsula. Strain 41(T) was found to be a Gram-positive bacterium, its cells being short, straight, motile rods. Chains of three to five cells were often observed. The isolate grew only chemolithoautotrophically on CO, producing equimolar quantities of H2 and CO2 (according to the equation CO+H2O --> CO2+H2). Growth was observed in the temperature range 40-68 degrees C, with an optimum at 58 degrees C, and in the pH range 6.5-7.6, with an optimum at pH 7.0. The generation time under optimal conditions for chemolithotrophic growth was 1.1 h. The DNA G+C content was 46 +/- 1 mol%. Growth was completely inhibited by penicillin, ampicillin, streptomycin, kanamycin and neomycin. On the basis of the phenotypic and phylogenetic features, it is proposed that this isolate represents a new genus and species, Carboxydocella thermautotrophica gen. nov., sp. nov. (type strain 41(T) = DSM 12356(T) = VKM B-2282(T)).

Nautilia lithotrophica gen. nov., sp. nov., a thermophilic sulfur-reducing epsilon-proteobacterium isolated from a deep-sea hydrothermal vent

A novel, strictly anaerobic, thermophilic sulfur-reducing bacterium, strain 525T, was isolated from tubes of the deep-sea hydrothermal vent polychaete Alvinella pompejana, collected on the East Pacific Rise (13 degrees N). This organism grew in the temperature range 37-68 degrees C, the optimum being 53 degrees C, and in the pH range 6.4-7.4, the optimum being 6.8-7.0. The NaCl range for growth was 0.8-5.0%, the optimum being 3.0%. Strain 525T grew lithoautotrophically with H2 as energy source, S0 as electron acceptor and CO2 as carbon source. Alternatively, strain 525T was able to use formate as an energy source. The G+C content of the genomic DNA was 34.7 mol%. Phylogenetic analysis of the 16S rDNA gene sequence placed strain 525T in the epsilon-subclass of the Proteobacteria, where it forms a deep cluster with recently isolated relatives. On the basis of phenotypic and phylogenetic differences between strain 525T and its closest phylogenetic relatives, it is proposed that the new isolate should be described as a member of a new genus, Nautilia, for which the name Nautilia lithotrophica gen. nov., sp. nov. is proposed. The type strain is strain 525T (= DSM 13520T).

[Amphibacillus fermentum sp. nov., Amphibacillus tropicus sp. nov.--new alkaliphilic, facultatively anaerobic, saccharolytic Bacilli from Lake Magadi]

New alkaliphilic, saccharolytic, rod-shaped, gram-positive bacteria resistant to heating and drying and phylogenetically affiliated to the Bacillus lineage were isolated under strictly anaerobic conditions from sediments of the alkaline and highly mineralized Lake Magadi. Strain Z-7792 forms endospores; in strain Z-7984, endospore formation was not revealed. The strains are capable of both anaerobic growth (at the expense of fermentation of glucose and certain mono- and disaccharides with the formation of formate, ethanol, and acetate) and aerobic growth. Among polysaccharides, the strains hydrolyze starch, glycogen, and xylan. Yeast extract or methionine are required for growth. The strains are strict alkaliphiles exhibiting obligate requirement for Na+ and carbonate ions but not for Cl- ion. Growth occurs at a total mineralization as high as 3.3-3.6 M Na+, with an optimum at 1-1.7 M Na+. Strain Z-7792 is an obligate alkaliphile with a pH growth range of 8.5-11.5 and an optimum of 9.5-9.7. Strain Z-7984 grows in a pH range of 7.0-10.5 with an optimum at 8.0-9.5. Both strains are mesophiles having a growth optimum at 37-38 degrees C. They belong to bacilli with a low G + C content. The G + C contents of the DNA of strains Z-7792 and Z-7984 are 39.2 and 41.5 mol%, respectively. These isolates of facultatively anaerobic, strictly alkaliphilic, Na(+)-dependent bacilli can be considered representatives of the ecological group adapted to the life at drying-up shoars of soda lakes. Because of their independence of NaCl and lack of obligate dependence on sodium carbonates, the isolates are to be assigned to athalassophilic organisms. According to their physiological and phylogenetic characteristics, they taxonomically belong to group 1 of the species of bacilli, occupying a position intermediate between the genera Amphibacillus and Gracilibacillus. The isolates are described as new species of Amphibacillus: A. fermentum (type strain, Z-7984T) and A. tropicus (type strain, Z-7792T).

Isolation and characterization of Thermococcus sibiricus sp. nov. from a Western Siberia high-temperature oil reservoir

Anaerobic organotrophic hyperthermophilic Archaea were isolated from five of eight samples from oil wells of the Samotlor oil reservoir (depth, 1,799-2,287 m; temperature, 60 degrees-84 degrees C). Three strains were isolated in pure cultures and characterized phylogenetically on the basis of comparison of the 16S rRNA gene sequences. All strains belonged to a new species of the genus Thermococcus, with Thermococcus litoralis, Thermococcus aggregans, Thermococcus fumicolans, and Thermococcus alcaliphilus being the nearest relatives (range of sequence similarity, 97.2%-98.8%). Strain MM 739 was studied in detail. The new isolate grew on peptides but not on carbohydrates. Elemental sulfur had a stimulatory effect on growth. The temperature range for growth was between 40 degrees and 88 degrees C, with the optimum at 78 degrees C; the pH range was 5.8 to 9.0, with the optimum around 7.3; and the salinity range was 0.5% to 7.0%, with the optimum at 1.8%-2.0%. The doubling time at optimal growth conditions was about 43 min. The G+C content of the DNA was 38.4 mol%. The DNA-DNA relatedness between strain MM 739 and T. litoralis was 27%; between strain MM 739 and T. aggregans, it was 22%. Based on the phenotypic and genomic differences with known Thermococcus species, the new species Thermococcus sibiricus is proposed. The isolation of a hyperthermophilic archaeum from a deep subsurface environment, significantly remote from shallow or abyssal marine hot vents, indicates the existence of a subterranean biosphere inhabited by indigenous hyperthermophilic biota.

[Halonatronum saccharophilum gen. nov. sp. nov--a new haloalkalophilic bacteria from the order Haloanaerobiales from Lake Magadi]

A new alkaliphilic and moderately halophilic chemoorganotrophic anaerobic bacterium (strain Z-7986), which is spore-forming, rod-shaped, and has a gram-negative cell wall pattern, was isolated from the coastal lagoon mud of the highly mineralized Lake Magadi (Kenya). The organism is an obligatorily carbonate- and sodium chloride-dependent. It is a motile peritrichously flagellated rod that has developed within 3-17% NaCl concentration (with an optimum at 7-12% NaCl) and within a pH range of 7.7-10.3 (with an optimum at pH values of 8-8.5). It is a moderate thermophile with a broad temperature optimum from 36-55 degrees C and a growth maximum at 60 degrees C. The bacterium catabolizes glucose, fructose, sucrose, maltose, starch, glycogen, N-acetyl-D-glucosamine, and, to a slight degree, peptone and yeast extract. Its anabolism requires yeast extract or casamino acids. Glucose fermentation yields formate, acetate, ethanol, H2, and CO2. The bacterium is sulfidetolerant and capable of the nonspecific reduction of S0 to H2S. The G + C content of the DNA is 34.4 mol %. The analysis of the 16S rRNA sequence revealed that strain Z-7986 belongs to the order Haloanaerobiales and represents a new genus in the family Halobacteroidaceae. We suggest calling the organism Halonatronum saccharophilum gen. nov. sp. nov. The type strain of this species is Z-7986T (= DSM13868, = Uniqem 211).

Carboxydobrachium pacificum gen. nov., sp. nov., a new anaerobic, thermophilic, CO-utilizing marine bacterium from Okinawa Trough

A new anaerobic, thermophilic, CO-utilizing marine bacterium, strain JMT, was isolated from a submarine hot vent in Okinawa Trough. Cells of strain JMT were non-motile thin straight rods, sometimes branching, with a cell wall of the Gram-positive type, surrounded with an S-layer. Chains of three to five cells were often observed. The isolate grew chemolithotrophically on CO, producing equimolar quantities of H2 and CO2 (according to the equation CO+H2O-->CO2+H2) and organotrophically on peptone, yeast extract, starch, cellobiose, glucose, galactose, fructose and pyruvate, producing H2, acetate and CO2. Growth was observed from 50 to 80 degrees C with an optimum at 70 degrees C. The optimum pH was 6.8-7.1. The optimum concentration of sea salts in the medium was 20.5-25.5 g l(-1). The generation time under optimal conditions was 7.1 h. The DNA G+C content was 33 mol %. Growth of isolate JMT was not inhibited by penicillin, but ampicillin, streptomycin, kanamycin and neomycin completely inhibited growth. The results of 16S rDNA sequence analysis revealed that strain JMT belongs to the Thermoanaerobacter phylogenetic group within the Bacillus-Clostridium subphylum of Gram-positive bacteria but represents a separate branch of this group. On the basis of morphological and physiological features and phylogenetic data, this isolate should be assigned to a new genus, for which the name Carboxydobrachium is proposed. The type species is Carboxydobrachium pacificum; the type strain is JMT (= DSM 12653T).

Acetobacterium tundrae sp nov, a new psychrophilic acetogenic bacterium from tundra soil

A new psychrophilic, anaerobic, acetogenic bacterium from the tundra wetland soil of Polar Ural is described. The organism fermented H2/CO2, formate, methanol, and several sugars to acetate as the sole end-product. The temperature range for growth was 1-30 degrees C with an optimum at 20 degrees C. The bacterium showed no growth at 32 degrees C. Cells were gram-positive, oval-shaped, flagellated rods 0.7-1.l x 1.1-4.0 microm in size when grown at 1-20 degrees C. At 25-30 degrees C, the cell size increased up to 2-3 x 10-15 microm due to a defect in cell division. The DNA G+C content of the organism was 39.2 mol%. Based upon 16S rDNA analysis and DNA-DNA reassociation studies, the organism was classified in the genus Acetobacterium as a new species, for which the name Acetobacterium tundrae sp. nov. is proposed. The type strain is Z-4493 (=DSM 9173T).

Acidilobus aceticus gen. nov., sp. nov., a novel anaerobic thermoacidophilic archaeon from continental hot vents in Kamchatka

New thermoacidophilic organisms that were able to grow anaerobically on starch were isolated from the acidic hot springs of Kamchatka. Strain 1904T, isolated from a hot spring of the Moutnovski volcano, was characterized in detail. Its cells were regular or irregular cocci that were 1-2 microm in diameter, non-motile, and had a cell envelope consisting of one layer of subunits. The new organism was a hyperthermophile, growing in the temperature range 60-92 degrees C (with an optimum at 85 degrees C), an acidophile, having the pH range for growth of 2.0-6.0 (with an optimum at 3.8), and an obligate anaerobe. It fermented starch, forming acetate as the main growth product. Other growth substrates were yeast extract, beef extract and soya extract. Growth on yeast extract, beef extract and soya extract was stimulated by elemental sulfur, which was reduced to H2S. Acetate, arabinose, cellulose, formate, fructose, galactose, glucose, glycine, guar gum, lichenan, malate, maltose, methanol, pectin, pyruvate, propionate, xylan, xylose or a mixture of amino acids failed to support growth both in the presence and the absence of sulfur. When starch was used as the growth substrate, yeast extract (100 mg l(-1)) was required as a growth factor. The G+C content of the DNA was found to be 53.8 mol%. Comparison of the complete 16S rDNA sequence with databases revealed that the new isolate belonged to the kingdom Crenarchaeota. It was not closely related to any described genera (showing sequence similarity below 90.8%) and formed a separate branch of the Crenarchaeota. On the basis of physiological differences and rRNA sequence data, a new genus--Acidilobus--is proposed, the type species being Acidilobus aceticus strain 1904T (= DSM 11585T).

Thermanaerovibrio velox sp. nov., a new anaerobic, thermophilic, organotrophic bacterium that reduces elemental sulfur, and emended description of the genus Thermanaerovibrio

A moderately thermophilic, organotrophic bacterium with vibrioid cells was isolated from a sample of a cyanobacterial mat from caldera Uzon, Kamchatka, Russia, and designated strain Z-9701T. Cells of strain Z-9701T were curved, Gram-negative rods, 0.5-0.7 x 2.5-5.0 microm in size, with tapering ends and with fast, wavy movement by means of lateral flagella located on the concave side of the cell. Colonies were small, white, irregular or round, 0.2 mm in diameter, and with even edges. Strain Z-9701T was an obligate anaerobe with a temperature optimum at 60-65 degrees C and a pH optimum at 7.3. It fermented glucose, fructose, mannose, N-acetyl-D-glucosamine, adonite, arginine, serine, peptone, yeast extract and Casamino acids. The fermentation products formed during growth on glucose were acetate, lactate, H2, CO2 and ethanol. Strain Z-9701T reduced elemental sulfur to H2S during organotrophic growth with glucose or peptides as energy and carbon sources. In the presence of S0, strain Z-9701T was capable of lithotrophic growth with molecular hydrogen as energy substrate and 0.1 g yeast extract l(-1) as carbon source. Sulfate, thiosulfate, nitrate, Fe(III) and sulfite were not reduced and did not stimulate growth. The G+C content of strain Z-9701T DNA was 54.6 mol%. The results of 16S rDNA sequence analyses revealed that strain Z-9701T belongs to the cluster within the Clostridium group formed by Thermanaerovibrio acidaminovorans, Dethiosulfovibrio peptidovorans, Anaerobaculum thermoterrenum and Aminobacterium colombiense, but the level of sequence similarity with the members of this cluster was not very high (87.6-92.2%). Among these organisms, Thermanaerovibrio acidaminovorans is phenotypically close to strain Z-9701T. However, the two organisms showed a relatively low level of similarity of their 16S rRNA sequences (92.2%) and of DNA-DNA hybridization (15 +/- 1%). Nevertheless, on the basis of the similar morphology and physiology of the new isolate and Thermanaerovibrio acidaminovorans, strain Z-9701T was placed in the genus Thermanaerovibrio and a new species, Thermanaerovibrio velox, proposed for it. The type strain is Z-9701T (= DSM 12556T).

Thermoanaerobacter siderophilus sp. nov., a novel dissimilatory Fe(III)-reducing, anaerobic, thermophilic bacterium

A thermophilic, anaerobic, spore-forming, dissimilatory Fe(III)-reducing bacterium, designated strain SR4T, was isolated from sediment of newly formed hydrothermal vents in the area of the eruption of Karymsky volcano on the Kamchatka peninsula. Cells of strain SR4T were straight-to-curved, peritrichous rods, 0.4-0.6 micron in diameter and 3.5-9.0 microns in length, and exhibited a slight tumbling motility. Strain SR4T formed round, refractile, heat-resistant endospores in terminally swollen sporangia. The temperature range for growth was 39-78 degrees C, with an optimum at 69-71 degrees C. The pH range for growth was 4.8-8.2, with an optimum at 6.3-6.5. Strain SR4T grew anaerobically with peptone as carbon source. Amorphous iron(III) oxide present in the medium stimulated the growth of strain SR4T; cell numbers increased with the concomitant accumulation of Fe(II). In the presence of Fe(III), strain SR4T grew on H2/CO2 and utilized molecular hydrogen. Strain SR4T reduced 9,10-anthraquinone-2,6-disulfonic acid, sulfite, thiosulfate, elemental sulfur and MnO2. Strain SR4T did not reduce nitrate or sulfate and was not capable of growth with O2. The fermentation products from glucose were ethanol, lactate, H2 and CO2. The G + C content of DNA was 32 mol%. 16S rDNA sequence analysis placed the organism in the genus Thermoanaerobacter. On the basis of physiological properties and phylogenetic analysis, it is proposed that strain SR4T (= DSM 12299T) should be assigned to a new species, Thermoanaerobacter siderophilus sp. nov.

Natronoincola histidinovorans gen. nov., sp. nov., A new alkaliphilic acetogenic anaerobe

Two strains, asporogenous Z-7940 and sporogenous Z-7939, of a moderately haloalkaliphilic, obligately anaerobic, fermentative bacteria, motile, with Gram-positive cell wall structure, were isolated from soda deposits in Lake Magadi, Kenya. Both strains are mesophilic and utilize only two amino acids, histidine and glutamate, with formation of acetate and ammonium as the main end products. Strain Z-7939 in addition is able to utilize pyruvate. DNA-DNA homology between strains Z-7940 and Z-7939 was 94%, indicating that in spite of phenotypic differences they belong to the same species. They are true alkaliphiles with a pH range for growth of the type strain Z-7940 from pH 8.0 to pH 10.5, optimum at pH 9.4. Both strains obligately depend on sodium and bicarbonate ions. The optimum salt concentration for growth of the type strain is 8-10% wt/vol and the range from 4% to 16%. The G+C content of strain Z-7940 is 31.9 mol% and the strain Z-7939 is 32.3 mol%. Analysis of 16S rDNA sequence of the type strain shows it to belong to cluster XI of the low G+C Gram-positive bacteria. On the basis of its distinct phylogenetic position and physiological properties, we propose a new genus and new species Natronoincola histidinovorans for these strains. The type strain is Z-7940 (=DSM 11416).

Desulfurella kamchatkensis sp. nov. and desulfurella propionica sp. nov., new sulfur-respiring thermophilic bacteria from Kamchatka thermal environments

Two strains of moderately thermophilic bacteria, which reduce elemental sulfur to hydrogen sulfide, were isolated from volcanic sources in Kamchatka. Strain K-119T was obtained from a thermophilic microbial community associated with Thermothrix thiopara, and strain U-8T was isolated from a cyanobacterial mat inhabiting a sulfide-rich hot spring. Cells of both strains are short Gram-negative rods, motile with one polar flagellum (strain K-119T) or non-motile (strain U-8T). Both strains are obligate anaerobes, have temperature otima of 54-55 degrees C and pH optima of 6.9-7.2. Molecular hydrogen, acetate, fumarate, malate, pyruvate, lactate and long-chain saturated fatty acids served as growth substrates for both species; strain U-8T was also able to grow on propionate. All substrates were oxidized completely, H2S and CO2 being the only metabolic products. Elemental sulfur was obligately required for growth of strain K-119T, whereas strain U-8T was able to grow also with thiosulfate as electron acceptor and on pyruvate without an external electron acceptor. The DNA G + C contents of strains K-119T and U-8T were 31.6 and 32.2 mol%, respectively. Phenotypic features and the results of 16S rRNA sequencing indicate the affiliation of the new isolates to the genus Desulfurella. The DNA-DNA hybridization with Desulfurella acetivorans was 40% for strain K-119T and 55% for strain U-8T; the DNA-DNA hybridization between the new isolates was 32%. Based on the results of morphological, physiological and phylogenetic studies the following two new species are proposed: Desulfurella kamchatkensis sp. nov. with the type strain K-119T (= DSM 10409T) and Desulfurella propionica sp. nov. with the type strain U-8T (= DSM 10410T).

Desulfonatronovibrio hydrogenovorans gen. nov., sp. nov., an alkaliphilic, sulfate-reducing bacterium

A new alkaliphilic, sulfate-reducing bacterium, strain Z-7935T (T = type strain), was isolated from a soda-depositing lake, Lake Magadi in Kenya. This organism is a motile vibrio which utilizes only hydrogen and formate as electron donors and sulfate, sulfite, and thiosulfate, but not sulfur, as electron acceptors. Thiosulfate is dismutated. Strain Z-7935T is an obligately sodium-dependent alkaliphile which grows in sodium carbonate medium and does not grow at pH 7; the maximum pH for growth is more than pH 10, and the optimum pH is 9.5 to 9.7. The optimum NaCl concentration for growth is 3% (wt/vol). The optimum temperature for growth is 37 degrees C. The G + C content of the DNA is 48.6 mol%. 16S ribosomal DNA sequence analysis revealed that strain Z-7935T represents a new lineage with genus status in the delta subclass of the Proteobacteria. The name Desulfonatronovibrio hydrogenovorans gen. nov., sp. nov. is proposed for this organism; the type strain of D. hydrogenovorans is strain Z-7935 (= DSM 9292).

Spirochaeta alkalica sp. nov., Spirochaeta africana sp. nov., and Spirochaeta asiatica sp. nov., alkaliphilic anaerobes from the Continental Soda Lakes in Central Asia and the East African Rift

During a study of microbial communities in athalassic bodies of water, three new species within the genus Spirochaeta were described. These are alkaliphilic Spirochaeta alkalica sp. nov. Z-7491 (DSM 8900) and halophilic S. africana sp. nov. Z-7692 (DSM 8902) from the soda-depositing Lake Magadi in Central Africa and haloalkaliphilic S. asiatica sp. nov. Z-7591 (DSM 8901) from Lake Khatyn, Central Asia. These mesophilic spirochetes develop at pHs of > 9 as anaerobic saccharolytic dissipotrophs. The DNA base compositions (moles percent G+C) of the strains were as follows: S. alkalica Z-7491, 57.1; S. africana Z-7692, 56.1; and S. asiatica Z-7591, 49.2. The optimum growth parameters (temperature, pH, and NaCl concentration [percent, wt/vol], respectively) were as follows: for S. alkalica Z-7491, 35 degrees C, 9.2, and 5 to 7%; for S. africana Z-7692, 35 degrees C, 9.3, and 5 to 7%; and for S. asiatica Z-7591, 35 degrees C, 8.9, and 3 to 6%. The products of glucose fermentation were acetate, hydrogen, ethanol, and lactate, in different proportions, for S. alkalica and S. africana; for S. asiatica, they were acetate, ethanol, and lactate. S. asiatica is strictly anaerobic, while S. alkalica and S. africana are rather aerotolerant. All three species group within the radiation of the majority of the species of the genus Spirochaeta. Studies of the genes encoding 16S rRNA indicate a possible fanning out of the phylogenetic tree of spirochetes.

[A new psychroactive bacterium, Clostridium fimentarium, isolated from cattle manure fermented at a low temperature]

A new psychroactive saccharolytic anaerobic organism was isolated from cattle manure digested at 6 degrees C. The organism is a Gram-positive oligosporous motile rod measuring 0.5-0.6 by 2.1-5.0 microns. It utilizes glucose, fructose, maltose, arabinose, xylose, cellobiose, galactose, and mannose. Fermentation products are acetate, ethanol, lactate, formate, H2, and CO2. Growth is possible within a temperature range of 1-30 degrees C, with an optimum at 20-25 degrees C, and a pH range of 5.5-8.3, with an optimum at 6.8. The DNA GC content is 35.6 mol %. The organism was classified as a new species of the genus Clostridium, C. fimetarium sp. nov. The type strain is Z-2189.