Pseudodesulfovibrio alkaliphilus, sp. nov., an alkaliphilic sulfate-reducing bacterium isolated from a terrestrial mud volcano.

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-C15:0, C16:0, C18:0, and iso-C17:1ω8. 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 3.23 Mb and the genomic DNA G + C content was 61.93 mol%. The genome contained all genes essential for dissimilatory 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).

Anaerotalea alkaliphila gen. nov., sp. nov., an alkaliphilic, anaerobic, fermentative bacterium isolated from a terrestrial mud volcano.

Diversity of extremophilic microorganisms in mud volcanoes is largely unexplored. Here, we report the isolation of a novel alkaliphilic, mesophilic, fermentative bacterium (strain F-3apT) from a terrestrial mud volcano located at the Taman peninsula, Russia. Cells of strain F-3apT are Gram-stain-positive non-motile rods. The formation of endospores is not observed. The temperature range for growth is 14-42 °C, with an optimum at 37 °C. The pH range for growth is 7.5-11.0, with an optimum at pH 9.0. The isolate utilizes various organic polymeric substances, organic acids, carbohydrates, and proteinaceous compounds. The end products of glucose fermentation are ethanol, CO2, and H2. The major cellular fatty acids of strain F-3apT are C16:0, C16:1, and C14:0. Phylogenetic analysis reveals that strain F-3apT belongs to the order Clostridiales, with less than 91% of 16S rRNA gene sequence similarity to any species with a validly published name. The total size of the genome of strain F-3apT is 2.98 Mb, and a genomic DNA G + C content is 56.78 mol%. The whole-genome phylogenetic analysis confirms that strain F-3apT forms a distinct lineage within Clostridia. We propose to assign strain F-3apT to a new species of a novel genus Anaerotalea alkaliphila gen. nov., sp. nov. The type strain is F-3apT (= KCTC 15917 T = VKM B-3406 T).

Alkalibaculum sporogenes sp. nov., isolated from a terrestrial mud volcano and emended description of the genus Alkalibaculum.

A novel anaerobic, endospore-forming bacterium (strain M08 DMBT) was isolated from a terrestrial mud volcano (Taman Peninsula, Russia). Cells of the strain were motile rods 1.3-2.0 µm long and 0.4 µm in diameter. The temperature range for growth was 5-42 °C, with an optimum at 30 °C. The pH range for growth was H 6.5-11.0, with an optimum at pH 8.0. Growth of strain M08 DMBT was observed at NaCl concentrations of 0-5.0 % (w/v) with an optimum at 1.0 %. Strain M08 DMBT utilized 3,4-dimethoxybenzoic acid, 2-methoxyphenol, carbon monoxide, glucose, fructose, mannose, xylose and yeast extract. The end product of glucose fermentation was acetate. The DNA G+C content of strain M08 DMBT was 32.3 mol% (obtained via whole genome sequencing). The closest phylogenetic relative of strain M08 DMBT was Alkalibaculum bacchi (family Eubacteriaceae, class Clostridia) with 95.17 % 16S rRNA gene sequence similarity. Based on the phenotypic, genotypic and phylogenetic characteristics of the isolate, strain M08 DMBT is considered to represent a novel species of the genus Alkalibaculum, for which the name Alkalibaculum sporogenes sp. nov. is proposed. The type strain of Alkalibaculum sporogenes is M08 DMBT (=KCTC 15840T=VKM B-3387T).

Calorimonas adulescens gen. nov., sp. nov., an anaerobic thermophilic bacterium utilizing methoxylated benzoates.

A novel anaerobic, thermophilic bacterium (strain A05 MBT) was isolated from Daginsky thermal springs (Sakhalin, Russia) on 2-methoxybenzoate as a substrate. Cells of the strain were motile long rods, 3.0-5.0 µm in length and 0.5-0.6 µm in diameter. The temperature range for growth was 47-68 °C, with an optimum at 60 °C. The pH range for growth was 4.5-8.0, with an optimum at pH 5.5-6.0. Strain A05 MBT did not require NaCl for growth. The strain utilized methoxylated aromatic compounds (2-methoxybenzoate and 3,4-dimethoxybenzoate), a number of carbohydrates (glucose, fructose, mannose, trehalose, xylose, sucrose, galactose, ribose, maltose, raffinose, lactose, cellobiose and dextrin) and proteinaceous substrates (yeast extract, beef extract, peptone and tryptone). The end products of glucose fermentation were acetate, ethanol and CO2. The DNA G+C content of strain A05 MBT was 40.2 mol% (whole-genome analysis). 16S rRNA gene sequence analysis revealed that strain A05MBT belongs to the order Thermoanaerobacterales (phylum Firmicutes). The closest relative of strain A05 MBT was Caloribacterium cisternae (94.3 % 16S rRNA gene sequence similarity). Based on the phenotypic, genotypic and phylogenetic characteristics of the isolate, strain A05 MBT is considered to represent a novel species of a new genus, for which the name Calorimonas adulescens gen. nov., sp. nov. is proposed. The type strain of Calorimonas adulescens is A05 MBT (=KCTC 15839T=VKM B-3388T).

Sulfurimonas crateris sp. nov., a facultative anaerobic sulfur-oxidizing chemolithoautotrophic bacterium isolated from a terrestrial mud volcano.

A novel mesophilic facultative anaerobic bacterium, strain SN118T, was isolated from a terrestrial mud volcano in Taman Peninsula, Russia. The cells were Gram-negative, motile, short, straight or curved rods with a single polar flagellum. Growth was observed at 5-40 °C (optimum, 30 °C) and pH 5.5-9.5 (optimum, pH 8.0). Growth of strain SN118T was observed in NaCl concentrations ranging from 0.5 to 8.0 % (w/v) with an optimum at 2.0-3.0 % (w/v). The isolate grew chemolithoautotrophically with sulfide, elemental sulfur or thiosulfate as electron donor, oxygen, nitrate or nitrite as an electron acceptor and CO2/HCO3 - as a carbon source. Molecular hydrogen or organic substances did not support growth. Nitrate was reduced to N2. The dominant fatty acids were C16 : 1ω7c, C16 : 0 and C18  :  1ω7c. The total size of the genome of the novel isolate was 2 209 279 bp and the genomic DNA G+C content was 38.8 mol%. Results of 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 denitrificans DSM 1251T (96.74 %). Based on its physiological properties and results from phylogenetic analyses, including average nucleotide identity and in silico DNA-DNA hybridization values, the isolate is considered to represent a novel species of the genus Sulfurimonas, for which the name Sulfurimonas crateris sp. nov. is proposed. The type strain is SN118T (=DSM 109248T=VKM B-3378T).

Pelomicrobium methylotrophicum gen. nov., sp. nov. a moderately thermophilic, facultatively anaerobic, lithoautotrophic and methylotrophic bacterium isolated from a terrestrial mud volcano.

A novel moderately thermophilic, bacterium, strain SM250T, was isolated from a terrestrial mud volcano, Taman peninsula, Krasnodar region, Russia. Cells of strain SM250T were Gram-negative non-spore forming motile straight rods. Growth was observed at temperatures 30-63 °C (optimum at 50 °C), pH 6.5-10.0 (optimum at pH 8.5) and NaCl concentrations 0-4.5% (w/v) (optimum at 1.0-1.5% (w/v)). The novel isolate grows by aerobic respiration or anaerobic respiration with nitrate as the terminal electron acceptor. Strain SM250T grows by the utilization of methanol, formate and a number of other organic compounds or lithoautotrophically with hydrogen, elemental sulfur or thiosulfate as electron donors. The total size of the genome of the novel isolate was 3,327,116 bp and a genomic DNA G + C content was 64.8 mol%. Analysis of the 16S rRNA gene sequences revealed that strain SM250T belongs to the class Hydrogenophilia within the phylum Proteobacteria, with less than 91% of 16S rRNA gene sequence similarity to any species with validly published name. We propose to assign strain SM250T to a new species of a novel genus Pelomicrobium methylotrophicum gen. nov., sp. nov. The type strain is SM250T (= KCTC 62861T = VKM B-3274T).

Tepidibaculum saccharolyticum gen. nov., sp. nov. a moderately thermophilic, anaerobic, spore-forming bacterium isolated from a terrestrial hot spring.

A novel moderately thermophilic, anaerobic bacterium, strain STR9T was isolated from terrestrial hot spring at Uzon Caldera, Kamchatka peninsula, Russia. Cells of strain STR9T were spore-forming motile straight or slightly curved rods 0.3 µm in diameter and 1.0-2.0 µm in length having a Gram-positive cell-wall structure. The temperature range for growth was 30-58 °C, with an optimum at 50 °C. The pH range for growth was 5.0-10.5, with an optimum at pH 8.0-9.0. NaCl inhibited growth of the strain STR9T and no growth was evident above 0.5% NaCl (w/v). Several mono-, di-, and polysaccharides as well as beef extract and yeast extract supported growth. The main end products of glucose fermentation were ethanol, acetate, hydrogen, and carbon dioxide. The G + C content of DNA of strain STR9T was 40.0 mol% (Tm). Analysis of the 16S rRNA gene sequences revealed that strain STR9T belongs to the family Ruminococcaceae, class Clostridia, with less than 93% 16S rRNA gene sequence similarity to any species with validly published name. We propose to assign strain STR9T to a new species of a novel genus Tepidibaculum saccharolyticum gen. nov., sp. nov. The type strain is STR9T (= DSM 28577T = VKM B-2882T = UNIQEM STR9T).

Desulfothermobacter acidiphilus gen. nov., sp. nov., a thermoacidophilic sulfate-reducing bacterium isolated from a terrestrial hot spring.

An anaerobic sulfate-reducing micro-organism, strain 3408-1T, was isolated from a terrestrial hot spring in Kamchatka peninsula (Russia). The cells were spore-forming rods with a Gram-positive type of cell wall. The new isolate was a moderately thermoacidophilic anaerobe able to grow either by sulfate or thiosulfate respiration with H2 or formate as substrates, or by fermenting yeast extract, maltose, sucrose, glucose and pyruvate. The fermentation products were acetate, CO2 and H2. The pH range for growth was 2.9-6.5, with an optimum at 4.5. The temperature range for growth was 42-70 °C, with an optimum at 55 °C. The G+C content of DNA was 58 mol%. Phylogenetic analysis of the 16S rRNA gene showed that strain 3408-1T belongs to the family Thermoanaerobacteraceae, order Thermoanaerobacterales and was distantly related to the species of the genus Ammonifex(93-94 % sequence similarity). On the basis of physiological properties and results of phylogenetic analysis, strain 3408-1T is considered to represent a novel species of a new genus, for which the name Desulfothermobacter acidiphilus gen. nov., sp. nov. is proposed. The type strain is 3408-1T (=DSM 105356T=VKM B-3183T).

Thermodesulfitimonas autotrophica gen. nov., sp. nov., a thermophilic, obligate sulfite-reducing bacterium isolated from a terrestrial hot spring.

A novel thermophilic, anaerobic, chemolithoautotrophic bacterium, strain SF97T, was isolated from a terrestrial hot spring (Kuril Islands, Russia). Cells of strain SF97T were rod-shaped and motile with a Gram-positive cell-wall type. The novel isolate grew at 45-72 °C (optimum 65 °C) and pH 5.5-8.5 (optimum 6.0-6.5). The strain grew chemolithoautotrophically with molecular hydrogen as an electron donor, sodium sulfite or SO2 gas as an electron acceptor and bicarbonate/CO2 as a carbon source. Sulfate, thiosulfate, elemental sulfur, Fe(III) or nitrate were not used as electron acceptors either with H2 or organic electron donors. Phylogenetic analysis based on 16S rRNA gene sequences indicated that the isolate belonged to the family Thermoanaerobacteraceae, order Thermoanaerobacterales, and was distantly related to species of the genus Ammonifex (92-93 % sequence similarity). On the basis of its physiological properties and results of phylogenetic analyses, strain SF97T is considered to represent a novel species of a new genus, for which the name Thermodesulfitimonas autotrophica gen. nov., sp. nov. is proposed. The type strain of Thermodesulfitimonas autotrophica is SF97T (=DSM 102936T=VKM B-2961T). T. autotrophica is the first reported obligate sulfite-reducing micro-organism.

Dissulfurimicrobium hydrothermale gen. nov., sp. nov., a thermophilic, autotrophic, sulfur-disproportionating deltaproteobacterium isolated from a hydrothermal pond.

A thermophilic, anaerobic, chemolithoautotrophic bacterium (strain Sh68T) was isolated from a hydrothermal pond at Uzon Caldera, Kamchatka, Russia, using anoxic medium with elemental sulfur as the only energy source. Cells of strain Sh68T were Gram-stain-negative rods, 0.5-0.8 µm in diameter and 1.2-2.0 µm in length, motile by means of flagella. The temperature range for growth was 30-65 °C, with an optimum at 50-52 °C. The pH range for growth was 5.2-7.5, with optimum growth at pH 6.0-6.2. Growth of strain Sh68T was observed at NaCl concentrations ranging from 0 to 2.3 % (w/v). Strain Sh68T 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 Sh68T 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 belongs to the class Deltaproteobacteria and is related most closely to Dissulfuribacter thermophilus S69T (90.0 % similarity). On the basis of its physiological properties and results of phylogenetic analyses, strain Sh68T is considered to represent a novel species of a new genus, for which the name Dissulfurimicrobium hydrothermale gen. nov., sp. nov. is proposed. The type strain of Dissulfurimicrobium hydrothermale is Sh68T ( = JCM 19990T = VKM B-2854T). This is the first description of a sulfur-disproportionating thermophile from a terrestrial ecosystem.

Hydrogenogenic and Sulfidogenic Growth of Thermococcus Archaea on Carbon Monoxide and Formate.

Enrichment and pure cultures of hyperthermophilic archaea capable of anaerobic growth on one- carbon compounds (CO and/or formate) were obtained from deep-sea sites of hydrothermal activity at the Mid-Atlantic Ridge, Lau Basin, and Guaymas Basin. All isolates belonged to the T barophilus-T paralvi- .nellae group within the genus Thermococcus. In all cases available for analysis, the genomes of Thermococcus strains capable of growth by hydrogenogenic utilization of CO and/or formate contained clusters of genes en- coding energy-converting hydrogenase and either CO dehydrogenase or formate dehydrogenase and formate transporter. Apart from the previously known processes of hydrogenogenic oxidation of CO and formate, the oxidation of these substrates coupled to sulfur reduction was observed, processes previously unknown among archaea. The capacities for hydrogenogenic or sulfidogenic oxidation of CO and formate occurred in the studied strains in all possible combinations, which could only in part be explained by peculiarities of organi- zation of genetic determinants revealed in the genomes. Investigation of CO and formate consumption kinet- ics revealed that T barophilus strain Ch5 was able to grow at concentrations close to the environmental ones. Thus, it was shown that hyperthermophilic archaea from deep-sea hydrothermal vents are able to utilize one- carbon substrates of abiotic origin both in the presence of an electron acceptor (sulfur) and in its absence. These processes were probably of importance under the conditions of the early Earth biosphere.

[Diversity of Cuproproteins and Copper Homeostasis Systems in Melioribacter roseus, a Facultatively Anaerobic Thermophilic Member of a New Phylum Ignavibacteriae].

The genome of Melioribacter roseus, one of two members of the recently described phylum Ignavibacteriae, was searched for the genes encoding proteins associated with copper transport or containing copper as cofactors, and the effect of Cu2+ concentration in the medium on M. roseus growth was investigated. Genomic analysis revealed a variety of copper-containing oxidoreductases in this facultative anaerobe. Three ATPases responsible for copper transport were identified. One of them (MROS_1511) was.probably involved in assembly of the copper-containing cytochrome c oxidase, while two others (MROS_0327 and MROS_0791) probably carried out a detoxification function. The presence of several copper-containing oxidoreductases and copper homeostasis systems in M. roseus is in agreement with the previously hypothesized origin of the phylum Ignavibacteriae from an aerobic ancestor common with those of Bacteroidetes and Chlorobi.

Tepidisphaera mucosa gen. nov., sp. nov., a moderately thermophilic member of the class Phycisphaerae in the phylum Planctomycetes, and proposal of a new family, Tepidisphaeraceae fam. nov., and a new order, Tepidisphaerales ord. nov.

Three strains of facultatively aerobic, moderately thermophilic bacteria were isolated from terrestrial hot springs in Baikal Lake region and Kamchatka (Russia). Cells of the new isolates were cocci reproducing by binary fission. The temperature range for growth was between 20 and 56 °C and the pH range for growth from pH 4.5 to 8.5, with optimal growth at 47-50 °C and pH 7.0-7.5. The organisms were chemoheterotrophs preferring sugars and polysaccharides as growth substrates. 16S rRNA gene sequences of strains 2842, 2813 and 2918Kr were nearly identical (99.7-100 % similarity) and indicated that the strains belonged to the phylum Planctomycetes. The phylogenetically closest cultivated relatives were Algisphaera agarilytica 06SJR6-2(T) and Phycisphaera mikurensis FYK2301M01(T) with 16S rRNA gene sequence similarity values of 82.4 and 80.3 %, respectively. The novel strains differed from them by higher growth temperature, sensitivity to NaCl concentration above 3.0 % and by their cellular fatty acids profile. On the basis of phylogenetic and physiological data, strains 2842(T), 2813 and 2918Kr represent a novel genus and species for which we propose the name Tepidisphaera mucosa sp. nov. The type strain is 2842(T) ( = VKM B-2832(T) = JCM 19875(T)). We also propose that Tepidisphaera gen. nov. is the type genus of a novel family, Tepidisphaeraceae fam. nov. and a novel order, Tepidisphaerales ord. nov.

Pyrobaculum ferrireducens sp. nov., a hyperthermophilic Fe(III)-, selenate- and arsenate-reducing crenarchaeon isolated from a hot spring.

A novel hyperthermophilic, anaerobic, archaeon was isolated from a terrestrial hot spring at Uzon Caldera, Kronotsky Nature Reserve, Kamchatka, Russia. The isolate, strain 1860(T), grew optimally at 90-95 °C and pH 6.0-7.0. The cells were non-motile straight rods, 1.5-5.0 µm in length, covered with surface-layer lattice. Strain 1860(T) utilized complex proteinaceous compounds as electron donors and ferrihydrite, Fe(III) citrate, nitrate, thiosulfate, selenite, selenate and arsenate as electron acceptors for growth. The sequence of the 16S rRNA gene of strain 1860(T) had 97.9-98.7 % similarity with those of members of the genus Pyrobaculum. On the basis of its physiological properties and phylogenetic analyses including in silico genome to genome hybridization, the isolate is considered to represent a novel species, for which the name Pyrobaculum ferrireducens sp. nov. is proposed. The type strain is 1860(T) ( = DSM 28942(T) = VKM B-2856(T)).

Mobilitalea sibirica gen. nov., sp. nov., a halotolerant polysaccharide-degrading bacterium.

A novel strictly anaerobic, halotolerant, organotrophic bacterium, strain P3M-3(T), was isolated from a microbial mat formed under the flow of hot water emerging from a 2775 m-deep well in Tomsk region (western Siberia, Russia). Cells of strain P3M-3(T) were straight and curved rods, 0.2-0.4 µm in width and 1.5-20 µm in length. Strain P3M-3(T) grew optimally at 37 °C, pH 7.0-7.5 and in a NaCl concentration of 15 g l(-1). Under optimum growth conditions, the doubling time was 1 h. The isolate was able to ferment a variety of mono-, di- and polysaccharides, including microcrystalline cellulose. Acetate, ethanol, H2 and CO2 were the main products of glucose fermentation. The DNA G+C content was 33.4 mol%. 16S rRNA gene-based phylogenetic analysis showed that strain P3M-3(T) was a member of family Lachnospiraceae, whose representatives are also found in Clostridium cluster XIVa. 16S rRNA gene sequence similarity with Clostridium jejuense HY-35-12(T), the closest relative, was 93.9%. A novel genus and species, Mobilitalea sibirica gen. nov., sp. nov., are proposed based on phylogenetic analysis and physiological properties of the novel isolate. The type strain of the type species is P3M-3(T) ( = DSM 26468(T) = VKM B-2804(T)).

[Capacity of hyperthermophilic Crenarchaeota for decomposition of refractory protiens (α- and ß-keratins)].

Anaerobic thermophilic archaea of the genera Thermogladius and Desulfurococcus capable of a- and P3-keratin decomposition were isolated from hot springs of Kamchatka and Kunashir Island. For two of them (strains 2355k and 3008g), the presence of high-molecular mass, cell-bound endopeptidases active against nonhydrolyzed and partially hydrolyzed proteins at high values of temperature and pH was shown. Capacity for ß-keratin decomposition was also found in collection strains (type strains of Desulfurococcus amylolyticus subsp. amylolyticus, D. mucosus subsp. mobilis, and D. fermentans).

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)).

Ornatilinea apprima gen. nov., sp. nov., a cellulolytic representative of the class Anaerolineae.

A novel obligately anaerobic, mesophilic, organotrophic bacterium, strain P3M-1(T), was isolated from a microbial mat formed in a wooden bath filled with hot water emerging from a 2775 m-deep well in the Tomsk region of western Siberia, Russia. Cells of strain P3M-1(T) were rod-shaped, 0.3-0.7 µm in width and formed multicellullar filaments that reached up to 400 µm in length. Strain P3M-1(T) grew optimally at 42-45 °C, pH 7.5-8.0, and with 0.1% (w/v) NaCl. Under optimal conditions, the doubling time was 6 h. The isolate was able to ferment a variety of proteinaceous substrates and sugars, including microcrystalline cellulose. Acetate, ethanol and H(2) were the main products of glucose fermentation. The genomic DNA G+C content was 55 mol%. 16S rRNA gene sequence-based phylogenetic analyses showed that strain P3M-1(T) was a member of the class Anaerolinea, with 92.8 % sequence similarity to Levilinea saccharolytica KIBI-1(T). Based on phylogenetic analysis and physiological properties, strain P3M-1(T) represents a novel species in a new genus, for which the name Ornatilinea apprima gen. nov., sp. nov. is proposed; the type strain of O. apprima is P3M-1(T) (= DSM 23815(T)=VKM B-2669(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 S69(T)) 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 S69(T) 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 S69(T) was observed at NaCl concentrations ranging from 0.9 to 5.0%, with an optimum at 1.8-2.7 (w/v). Strain S69(T) 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 S69(T) 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 S69(T) 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 S69(T) (=DSM 25762(T)=VKM B-2760(T)).

Moorella humiferrea sp. nov., a thermophilic, anaerobic bacterium capable of growth via electron shuttling between humic acid and Fe(III).

An anaerobic, thermophilic, spore-forming bacterium (strain 64-FGQ(T)) was isolated from a terrestrial hydrothermal spring from the Kamchatka peninsula, Russia. This strain utilized lactate as an electron donor, insoluble poorly crystalline Fe(III) oxide incorporated into alginate beads as a potential electron acceptor and 9,10-anthraquinone-2,6-disulfonate (AQDS) as an electron-shuttling compound. Vegetative cells of strain 64-FGQ(T) were Gram-stain-positive, peritrichously flagellated, motile, straight rods, 0.3-0.5 µm in diameter and 2.0-5.0 µm long, growing singly or forming short chains. Cells formed round refractive endospores in terminal swollen sporangia. The temperature range for growth was 46-70 °C, with an optimum at 65 °C. The pH range for growth was 5.5-8.5, with an optimum at pH 7.0. The substrates utilized by strain 64-FGQ(T) in the presence of AQDS as an electron acceptor included lactate, malate, succinate, glycerol and yeast extract. The strain fermented galactose, fructose, maltose, sucrose, pyruvate and peptone. Strain 64-FGQ(T) used AQDS, humic acid, thiosulfate, nitrate and perchlorate as electron acceptors for growth. Fe(III) was not directly reduced, but strain 64-FGQ(T) was able to grow and reduce Fe(III) oxide in the presence of small amounts of AQDS or humic acid as electron-shuttling compounds. The G+C content of the DNA of strain 64-FGQ(T) was 51 mol%. 16S rRNA gene sequence analysis placed the isolate in the genus Moorella, with the type strain of Moorella glycerini as its closest relative (97.2% similarity). Based on phylogenetic analysis and physiological characteristics, strain 64-FGQ(T) is considered to represent a novel species of the genus Moorella, for which the name Moorella humiferrea sp. nov. is proposed; the type strain is 64-FGQ(T) (=DSM 23265(T)=VKM B-2603(T)).