Pseudodesulfovibrio pelocollis sp. nov. a Sulfate-Reducing Bacterium Isolated from a Terrestrial Mud Volcano.

Terrestrial mud volcanoes (TMVs), surface expressions of a deep-subterranean sedimentary volcanism, are widespread throughout the world. The methane and sulfur cycles are recognized as the most important biogeochemical cycles in these environments. Only few anaerobic bacterial strains were recovered from TMVs. We have isolated a novel sulfate-reducing bacterium (strain SB368T) from TMV located at Taman Peninsula, Russia. Optimum growth of strain SB368T was observed at 30 °C, pH 8.0 and 1% NaCl. Strain SB368T utilized lactate, pyruvate and fumarate in the presence of sulfate, sulfite or thiosulfate. Growth with molecular hydrogen was observed only in the presence of acetate. Fermentative growth occurred on pyruvate. Phylogenetic analysis revealed that strain SB368T belongs to the genus Pseudodesulfovibrio but is distinct from all described species. Based on its genomic and phenotypic properties, a new species, Pseudodesulfovibrio pelocollis sp. nov. is proposed with strain SB368T (= DSM 111087 T = VKM B-3585 T) as a type strain.

Sedimenticola hydrogenitrophicus sp. nov. a chemolithoautotrophic bacterium isolated from a terrestrial mud volcano, and proposal of Sedimenticolaceae fam. nov. in the order Chromatiales.

Chemolithoautotrophic microorganisms can play a significant role in the biogeochemical cycling of elements in deep-subsurface-associated environments. A novel facultatively anaerobic lithoautotrophic bacteria (strains SB48T and SN1189) were isolated from terrestrial mud volcanoes (Krasnodar Krai, Russia). Cells of the strains were straight motile rods. Growth was observed at temperatures up to 35 °C (optimum at 30 °C), pH 6.0-8.5 (optimum at pH 7.5) and NaCl concentrations of 0.5-4.0% (w/v) (optimum at 1.5-2.0% (w/v)). The isolates grew chemolithoautotrophically with molecular hydrogen or thiosulfate as an electron donor, nitrate as an electron acceptor and CO2/HCO3- as a carbon source. They also grew with organic acids, ethanol, yeast extract and peptone. The isolates were capable of either anaerobic respiration with nitrate or nitrous oxide as the electron acceptors or aerobic respiration under microaerobic condition. The total size of the genome of strains SB48T and SN1189 was 4.71 and 5.13 Mbp, respectively. Based on phenotypic and phylogenetic characteristics, strains SB48T and SN1189 represent a novel species of the genus Sedimenticola, S. hydrogenitrophicus (the type strain is SB48T = KCTC 25568 T = VKM B-3680 T). The new isolates are the first representatives of the genus Sedimenticola isolated from a terrestrial ecosystem. Based on phylogenomic reconstruction we propose to include the genus Sedimenticola and the related genera into a new family Sedimenticolaceae fam. nov. within the order Chromatiales.

Composition and Metabolic Potential of Fe(III)-Reducing Enrichment Cultures of Methanotrophic ANME-2a Archaea and Associated Bacteria.

The key microbial group involved in anaerobic methane oxidation is anaerobic methanotrophic archaea (ANME). From a terrestrial mud volcano, we enriched a microbial community containing ANME-2a, using methane as an electron donor, Fe(III) oxide (ferrihydrite) as an electron acceptor, and anthraquinone-2,6-disulfonate as an electron shuttle. Ferrihydrite reduction led to the formation of a black, highly magnetic precipitate. A significant relative abundance of ANME-2a in batch cultures was observed over five subsequent transfers. Phylogenetic analysis revealed that, in addition to ANME-2a, two bacterial taxa belonging to uncultured Desulfobulbaceae and Anaerolineaceae were constantly present in all enrichments. Metagenome-assembled genomes (MAGs) of ANME-2a contained a complete set of genes for methanogenesis and numerous genes of multiheme c-type cytochromes (MHC), indicating the capability of methanotrophs to transfer electrons to metal oxides or to a bacterial partner. One of the ANME MAGs encoded respiratory arsenate reductase (Arr), suggesting the potential for a direct coupling of methane oxidation with As(V) reduction in the single microorganism. The same MAG also encoded uptake [NiFe] hydrogenase, which is uncommon for ANME-2. The MAG of uncultured Desulfobulbaceae contained genes of dissimilatory sulfate reduction, a Wood-Ljungdahl pathway for autotrophic CO2 fixation, hydrogenases, and 43 MHC. We hypothesize that uncultured Desulfobulbaceae is a bacterial partner of ANME-2a, which mediates extracellular electron transfer to Fe(III) oxide.

Moorella sulfitireducens sp. nov., a thermophilic anaerobic bacterium isolated from a terrestrial thermal spring.

In hydrothermal ecosystems, the dissolution of sulfur dioxide in water results in the formation of sulfite, which can be used in microbial metabolism. A limited number of thermophiles have been isolated using sulfite as an electron acceptor. From a terrestrial thermal spring, Sakhalin Island, Russia, we isolated a thermophilic anaerobic bacterium (strain SLA38T). Cells of strain SLA38T were spore-forming straight rods. Growth was observed at temperatures 45-65 °C (optimum at 60 °C) and pH 5.5-9.0 (optimum at pH 6.5-7.0). The novel isolate was capable of anaerobic respiration with sulfite, thiosulfate, fumarate and perchlorate or fermentative growth. Strain SLA38T utilized glycerol, lactate, pyruvate and yeast extract. It grew lithoautotrophically on carbon monoxide with thiosulfate as electron acceptor, producing acetate. The genome size of the isolate was 2.9 Mbp and genomic DNA G + C content was 53.6 mol%. Analysis of the 16S rRNA gene sequences revealed that strain SLA38T belongs to the genus Moorella. Based on the physiological features and phylogenetic analysis, we propose to assign strain SLA38T to a new species of the genus Moorella, as Moorella sulfitireducens sp. nov. The type strain is SLA38T (= DSM 111068T = VKM B-3584T).

Lithoautotrophic lifestyle of the widespread genus Roseovarius revealed by physiological and genomic characterization of Roseovarius autotrophicus sp. nov.

The genus Roseovarius, a member of the ecologically important Roseobacter-clade, is widespread throughout the world. A facultatively anaerobic lithoautotrophic bacterium (strain SHN287T), belonging to the genus Roseovarius, was isolated with molecular hydrogen as an electron donor and nitrate as an electron acceptor from a terrestrial mud volcano. Strain SHN287T possessed metabolic features not reported for Roseovarius such as chemolithoautotrophic growth with oxidation of molecular hydrogen or sulfur compounds, anaerobic growth and denitrification. Based on the phenotypic and phylogenetic characteristics, the new isolate is considered to represent a novel species of the genus Roseovarius, for which the name Roseovarius autotrophicus sp. nov. is proposed. The type strain is SHN287T (= KCTC 15916T = VKM B-3404T). An amended description of the genus Roseovarius is provided. Comparison of 46 Roseovarius genomes revealed that (i) a full set of genes for the Calvin-Benson cycle is present only in two strains: SHN287T and Roseovarius salinarum; (ii) respiratory H2-uptake [NiFe] hydrogenases are specific for a phylogenetically distinct group, including SHN287T-related strains; (iii) the Sox enzymatic complex is encoded in most of the studied genomes; and (iv) denitrification genes are widespread and randomly distributed among the genus. The metabolic characteristics found in R. autotrophicus sp. nov. expand the ecological role of the genus Roseovarius.

Physiological and Genomic Characterization of a Hyperthermophilic Archaeon Archaeoglobus neptunius sp. nov. Isolated From a Deep-Sea Hydrothermal Vent Warrants the Reclassification of the Genus Archaeoglobus.

Hyperthermophilic archaea of the genus Archaeoglobus are the subject of many fundamental and biotechnological researches. Despite their significance, the class Archaeoglobi is currently represented by only eight species obtained as axenic cultures and taxonomically characterized. Here, we report the isolation and characterization of a new species of Archaeoglobus from a deep-sea hydrothermal vent (Mid-Atlantic Ridge, TAG) for which the name Archaeoglobus neptunius sp. nov. is proposed. The type strain is SE56T (=DSM 110954T = VKM B-3474T). The cells of the novel isolate are motile irregular cocci growing at 50-85°C, pH 5.5-7.5, and NaCl concentrations of 1.5-4.5% (w/v). Strain SE56T grows lithoautotrophically with H2 as an electron donor, sulfite or thiosulfate as an electron acceptor, and CO2/HCO3 - as a carbon source. It is also capable of chemoorganotrophic growth by reduction of sulfate, sulfite, or thiosulfate. The genome of the new isolate consists of a 2,115,826 bp chromosome with an overall G + C content of 46.0 mol%. The whole-genome annotation confirms the key metabolic features of the novel isolate demonstrated experimentally. Genome contains a complete set of genes involved in CO2 fixation via reductive acetyl-CoA pathway, gluconeogenesis, hydrogen and fatty acids oxidation, sulfate reduction, and flagellar motility. The phylogenomic reconstruction based on 122 conserved single-copy archaeal proteins supported by average nucleotide identity (ANI), average amino acid identity (AAI), and alignment fraction (AF) values, indicates a polyphyletic origin of the species currently included into the genus Archaeoglobus, warranting its reclassification.

Genetic Potential of Dissulfurimicrobium hydrothermale, an Obligate Sulfur-Disproportionating Thermophilic Microorganism.

The biochemical pathways of anaerobic sulfur disproportionation are only partially deciphered, and the mechanisms involved in the first step of S0-disproportionation remain unknown. Here, we present the results of sequencing and analysis of the complete genome of Dissulfurimicrobium hydrothermale strain Sh68T, one of two strains isolated to date known to grow exclusively by anaerobic disproportionation of inorganic sulfur compounds. Dissulfurimicrobium hydrothermale Sh68T is a motile, thermophilic, anaerobic, chemolithoautotrophic microorganism isolated from a hydrothermal pond at Uzon caldera, Kamchatka, Russia. It is able to produce energy and grow by disproportionation of elemental sulfur, sulfite and thiosulfate. Its genome consists of a circular chromosome of 2,025,450 base pairs, has a G + C content of 49.66% and a completion of 97.6%. Genomic data suggest that CO2 assimilation is carried out by the Wood-Ljungdhal pathway and that central anabolism involves the gluconeogenesis pathway. The genome of strain Sh68T encodes the complete gene set of the dissimilatory sulfate reduction pathway, some of which are likely to be involved in sulfur disproportionation. A short sequence protein of unknown function present in the genome of strain Sh68T is conserved in the genomes of a large panel of other S0-disproportionating bacteria and was absent from the genomes of microorganisms incapable of elemental sulfur disproportionation. We propose that this protein may be involved in the first step of elemental sulfur disproportionation, as S0 is poorly soluble and unable to cross the cytoplasmic membrane in this form.

Complete genome sequence of Thermosulfurimonas marina SU872T, an anaerobic thermophilic chemolithoautotrophic bacterium isolated from a shallow marine hydrothermal vent.

Thermosulfurimonas marina strain SU872T is a thermophilic, anaerobic, chemolithoautotrophic bacterium, isolated from a shallow-sea hydrothermal vent in the Pacific Ocean near Kunashir Island, that is able to grow by disproportionation of inorganic sulfur compounds and dissimilatory nitrate reduction to ammonium. Here we report the complete genome sequence of strain SU872T, which presents one circular chromosome of 1,763,258 bp with a mean G + C content of 58.9 mol%. The complete genome harbors 1827 predicted protein-encoding genes, 47 tRNA genes and 3 rRNA genes. Genes involved in sulfur and nitrogen metabolism were identified. This study expands our knowledge of sulfur and nitrogen use in energy metabolism of high temperatures areas of shallow-sea hydrothermal environments. In order to highlight Thermosulfurimonas marina metabolic features, its genome was compared with that of Thermosulfurimonas dismutans, the only other species described within the Thermosulfurimonas genus.

Genome analysis of Thermosulfuriphilus ammonigenes ST65T, an anaerobic thermophilic chemolithoautotrophic bacterium isolated from a deep-sea hydrothermal vent.

Thermosulfuriphilus ammonigenes ST65T is an anaerobic thermophilic bacterium isolated from a deep-sea hydrothermal vent chimney. T. ammonigenes is an obligate chemolithoautotroph utilizing elemental sulfur as an electron donor and nitrate as an electron acceptor with sulfate and ammonium formation. It also is able to grow by disproportionation of elemental sulfur, thiosulfate and sulfite. Here, we present the complete genome sequence of strain ST65T. The genome consists of a single chromosome of 2,287,345 base pairs in size and has a G + C content of 51.9 mol%. The genome encodes 2172 proteins, 48 tRNA genes, and 3 rRNA genes. Genome analysis revealed a complete set of genes essential to CO2 fixation and gluconeogenesis. Homologs of genes encoding known enzyme systems for nitrate ammonification are absent in the genome of T. ammonigenes assuming unique mechanism for this pathway. The genome of strain ST65T encodes a complete set of genes necessary for dissimilatory sulfate reduction, which are probably involved in sulfur disproportionation and anaerobic oxidation. This is the first reported genome of a bacterium from the genus Thermosulfuriphilus, providing insights into the microbial contribution into carbon, sulfur and nitrogen cycles in the deep-sea hydrothermal vent environment.

Genomic Characterization and Environmental Distribution of a Thermophilic Anaerobe Dissulfurirhabdus thermomarina SH388T Involved in Disproportionation of Sulfur Compounds in Shallow Sea Hydrothermal Vents.

Marine hydrothermal systems are characterized by a pronounced biogeochemical sulfur cycle with the participation of sulfur-oxidizing, sulfate-reducing and sulfur-disproportionating microorganisms. The diversity and metabolism of sulfur disproportionators are studied to a much lesser extent compared with other microbial groups. Dissulfurirhabdus thermomarina SH388T is an anaerobic thermophilic bacterium isolated from a shallow sea hydrothermal vent. D. thermomarina is an obligate chemolithoautotroph able to grow by the disproportionation of sulfite and elemental sulfur. Here, we present the results of the sequencing and analysis of the high-quality draft genome of strain SH388T. The genome consists of a one circular chromosome of 2,461,642 base pairs, has a G + C content of 71.1 mol% and 2267 protein-coding sequences. The genome analysis revealed a complete set of genes essential to CO2 fixation via the reductive acetyl-CoA (Wood-Ljungdahl) pathway and gluconeogenesis. The genome of D. thermomarina encodes a complete set of genes necessary for the dissimilatory reduction of sulfates, which are probably involved in the disproportionation of sulfur. Data on the occurrences of Dissulfurirhabdus 16S rRNA gene sequences in gene libraries and metagenome datasets showed the worldwide distribution of the members of this genus. This study expands our knowledge of the microbial contribution into carbon and sulfur cycles in the marine hydrothermal environments.

Genomic Insights into the Carbon and Energy Metabolism of a Thermophilic Deep-Sea Bacterium Deferribacter autotrophicus Revealed New Metabolic Traits in the Phylum Deferribacteres.

Information on the biochemical pathways of carbon and energy metabolism in representatives of the deep lineage bacterial phylum Deferribacteres are scarce. Here, we report the results of the sequencing and analysis of the high-quality draft genome of the thermophilic chemolithoautotrophic anaerobe Deferribacter autotrophicus. Genomic data suggest that CO2 assimilation is carried out by recently proposed reversible tricarboxylic acid cycle ("roTCA cycle"). The predicted genomic ability of D. autotrophicus to grow due to the oxidation of carbon monoxide was experimentally proven. CO oxidation was coupled with the reduction of nitrate to ammonium. Utilization of CO most likely involves anaerobic [Ni, Fe]-containing CO dehydrogenase. This is the first evidence of CO oxidation in the phylum Deferribacteres. The genome of D. autotrophicus encodes a Nap-type complex of nitrate reduction. However, the conversion of produced nitrite to ammonium proceeds via a non-canonical pathway with the participation of hydroxylamine oxidoreductase (Hao) and hydroxylamine reductase. The genome contains 17 genes of putative multiheme c-type cytochromes and "e-pilin" genes, some of which are probably involved in Fe(III) reduction. Genomic analysis indicates that the roTCA cycle of CO2 fixation and putative Hao-enabled ammonification may occur in several members of the phylum Deferribacteres.

Thermosulfuriphilus ammonigenes gen. nov., sp. nov., a thermophilic, chemolithoautotrophic bacterium capable of respiratory ammonification of nitrate with elemental sulfur.

An extremely thermophilic, anaerobic, chemolithoautotrophic bacterium (strain ST65T) was isolated from a deep-sea hydrothermal vent chimney located on the Eastern Lau Spreading Centre in the south-western Pacific Ocean, at a depth of 1870 m. Cells of strain ST65T were non-motile straight or slightly curved short rods, 0.5-0.6 µm in diameter and 0.8-1.5 µm in length. The temperature range for growth was 47-75 °C, with an optimum at 65 °C. The pH range for growth was 5.5-7.5, with an optimum at pH 6.5. Growth of strain ST65T was observed at NaCl concentrations ranging from 1.5 to 4.5 % (w/v), with an optimum at 2.0-2.5 %. Strain ST65T grew anaerobically with inorganic carbon as a carbon source and with elemental sulfur as an electron donor and nitrate as an electron acceptor producing sulfate and ammonium. It was also able to grow by disproportionation of elemental sulfur, thiosulfate and sulfite. Sulfate was not utilized as an electron acceptor. Analysis of the 16S rRNA gene sequence revealed that the isolate belongs to a deep lineage in the phylum Thermodesulfobacteria. On the basis of its physiological properties and results of phylogenetic analyses, it is proposed that the isolate represents a novel species of a new genus, Thermosulfuriphilus ammonigenes gen. nov., sp. nov. ST65T (=DSM 102941T=VKM B-2855T) is the type strain of the type species.

Respiratory Ammonification of Nitrate Coupled to Anaerobic Oxidation of Elemental Sulfur in Deep-Sea Autotrophic Thermophilic Bacteria.

Respiratory ammonification of nitrate is the microbial process that determines the retention of nitrogen in an ecosystem. To date, sulfur-dependent dissimilatory nitrate reduction to ammonium has been demonstrated only with sulfide as an electron donor. We detected a novel pathway that couples the sulfur and nitrogen cycles. Thermophilic anaerobic bacteria Thermosulfurimonas dismutans and Dissulfuribacter thermophilus, isolated from deep-sea hydrothermal vents, grew autotrophically with elemental sulfur as an electron donor and nitrate as an electron acceptor producing sulfate and ammonium. The genomes of both bacteria contain a gene cluster that encodes a putative nitrate ammonification enzyme system. Nitrate reduction occurs via a Nap-type complex. The reduction of produced nitrite to ammonium does not proceed via the canonical Nrf system because nitrite reductase NrfA is absent in the genomes of both microorganisms. The genome of D. thermophilus encodes a complete sulfate reduction pathway, while the Sox sulfur oxidation system is missing, as shown previously for T. dismutans. Thus, in high-temperature environments, nitrate ammonification with elemental sulfur may represent an unrecognized route of primary biomass production. Moreover, the anaerobic oxidation of sulfur compounds coupled to growth has not previously been demonstrated for the members of Thermodesulfobacteria or Deltaproteobacteria, which were considered exclusively as participants of the reductive branch of the sulfur cycle.

Microbial diversity and autotrophic activity in Kamchatka hot springs.

Microbial communities of Kamchatka Peninsula terrestrial hot springs were studied using molecular, radioisotopic and cultural approaches. Analysis of 16S rRNA gene fragments performed by means of high-throughput sequencing revealed that aerobic autotrophic sulfur-oxidizing bacteria of the genus Sulfurihydrogenibium (phylum Aquificae) dominated in a majority of streamers. Another widely distributed and abundant group was that of anaerobic bacteria of the genus Caldimicrobium (phylum Thermodesulfobacteria). Archaea of the genus Vulcanisaeta were abundant in a high-temperature, slightly acidic hot spring, where they were accompanied by numerous Nanoarchaeota, while the domination of uncultured Thermoplasmataceae A10 was characteristic for moderately thermophilic acidic habitats. The highest rates of inorganic carbon assimilation determined by the in situ incubation of samples in the presence of 14C-labeled bicarbonate were found in oxygen-dependent streamers; in two sediment samples taken from the hottest springs this process, though much weaker, was found to be not dependent on oxygen. The isolation of anaerobic lithoautotrophic prokaryotes from Kamchatka hot springs revealed a wide distribution of the ability for sulfur disproportionation, a new lithoautotrophic process capable to fuel autonomous anaerobic ecosystems.

Dissulfurirhabdus thermomarina gen. nov., sp. nov., a thermophilic, autotrophic, sulfite-reducing and disproportionating deltaproteobacterium isolated from a shallow-sea hydrothermal vent.

A thermophilic, anaerobic, chemolithoautotrophic bacterium, strain SH388T, was isolated from a shallow, submarine hydrothermal vent (Kuril Islands, Russia). Cells of strain SH388T were Gram-stain-negative short rods, 0.2-0.4 µm in diameter and 1.0-2.5 µm in length, and motile with flagella. The temperature range for growth was 25-58 °C (optimum 50 °C), and the pH range for growth was pH 5.0-7.0 (optimum pH 6.0-6.5). Growth of strain SH388T was observed in the presence of NaCl concentrations ranging from 0.5 to 4.0 % (w/v) (optimum 2.0-2.5 %). The strain grew chemolithoautotrophically with molecular hydrogen as electron donor, sodium sulfite as electron acceptor and bicarbonate/CO2 as a carbon source. It was also able to grow by disproportionation of sulfite and elemental sulfur but not thiosulfate. Sulfate, Fe(III) and 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 class Deltaproteobacteria and was most closely related to Dissulfuribacter thermophilus and Dissulfurimicrobium hydrothermale (91.6 % and 90.4 % sequence similarity). On the basis of its physiological properties and results of phylogenetic analyses, strain SH388T is considered to represent a novel species of a new genus, for which the name Dissulfurirhabdus thermomarina gen. nov., sp. nov. is proposed. The type strain of the species is SH388T (=DSM 100025T=VKM B-2960T). It is the first thermophilic disproportionator of sulfur compounds isolated from a shallow-sea environment.

Inmirania thermothiophila gen. nov., sp. nov., a thermophilic, facultatively autotrophic, sulfur-oxidizing gammaproteobacterium isolated from a shallow-sea hydrothermal vent.

A novel thermophilic, facultatively autotrophic bacterium, strain S2479T, was isolated from a thermal spring located in a tidal zone of a geothermally heated beach (Kuril Islands, Russia). Cells of strain S2479T were rod-shaped and motile with a Gram-negative cell-wall type. The temperature range for growth was 35-68 °C (optimum 65 °C), and the pH range for growth was pH 5.5-8.8 (optimum pH 6.5). Growth of strain S2479T was observed in the presence of NaCl concentrations ranging from 0.5 to 3.5 % (w/v) (optimum 1.5-2.0 %). The strain oxidized sulfur and thiosulfate as sole energy sources for autotrophic growth under anaerobic conditions with nitrate as electron acceptor. Strain S2479T was also capable of heterotrophic growth by reduction of nitrate with oxidation of low-chain fatty acids and a limited number of other carboxylic acids or with complex proteinaceous compounds. Nitrate was reduced to N2. Sulfur compounds were oxidized to sulfate. Strain S2479T did not grow aerobically during incubation at atmospheric concentration of oxygen but was able to grow microaerobically (1 % of oxygen in gas phase). Phylogenetic analysis based on 16S rRNA gene sequences indicated that the strain was a member of the family Ectothiorhodospiraceae, order Chromatiales, class Gammaproteobacteria. On the basis of phylogenetic and phenotypic properties, strain S2479T represents a novel species of a new genus, for which the name Inmirania thermothiophila gen. nov., sp. nov. is proposed. The type strain of the type species is S2479T ( = DSM 100275T = VKM B-2962T).

Thermostilla marina gen. nov., sp. nov., a thermophilic, facultatively anaerobic planctomycete isolated from a shallow submarine hydrothermal vent.

A novel thermophilic planctomycete (strain SVX8T) was isolated from a shallow submarine hydrothermal vent, Vulcano Island, Italy. The temperature range for growth was 30-68 °C, with an optimum at 55 °C. The pH range for growth was 5.0-9.0, with an optimum at pH 7.0-8.0. Growth was observed at NaCl concentrations ranging from 0.8 to 4.5 % (w/v) with an optimum at 2.5-3.5 % (w/v). The isolate grew anaerobically using a number of mono-, di- and polysaccharides as electron donors and nitrate or elemental sulfur as electron acceptors or by fermentation. Nitrate was reduced to nitrite; sulfur was reduced to sulfide. Strain SVX8T did not grow at atmospheric concentration of oxygen but grew microaerobically (up to 2 % oxygen in the gas phase). The G+C content of the DNA of strain SVX8T was 58.5 mol%. Based on phylogenetic position and phenotypic features, the new isolate is considered to represent a novel species belonging to a new genus in the order Planctomycetales, for which the name Thermostilla marina gen. nov., sp. nov. is proposed. The type strain of Thermostilla marina is SVX8T ( = JCM 19992T = VKM B-2881T). Strain SVX8T is the first thermophilic planctomycete isolated from a marine environment.

Thermogutta terrifontis gen. nov., sp. nov. and Thermogutta hypogea sp. nov., thermophilic anaerobic representatives of the phylum Planctomycetes.

Two novel strains of thermophilic planctomycetes were recovered from terrestrial and subterranean habitats. Strain R1(T) was isolated from a hot spring (Kunashir Island, Russia) and strain SBP2(T) was isolated from a deep gold mine (South Africa). Both isolates grew in the temperature range 30-60 °C and pH range 5.0-8.0. Strain R1(T) grew optimally at 60 °C and pH 6.0-6.5; for SBP2(T) optimal conditions were at 52 °C and pH 7.5-8.0. Both strains were capable of anaerobic respiration with nitrate and nitrite as electron acceptors as well as of microaerobic growth. They also could grow by fermentation of mono-, di- and polysaccharides. Based on their phylogenetic position and phenotypic features we suggest that the new isolates represent two novel species belonging to a new genus in the order Planctomycetales, for which the names Thermogutta terrifontis gen. nov., sp. nov. and Thermogutta hypogea sp. nov. are proposed. The type strain of Thermogutta terrifontis, the type species of the genus, is R1(T) ( = DSM 26237(T) = VKM B-2805(T)), and the type strain of Thermogutta hypogea is SBP2(T) ( = JCM 19991(T) = VKM B-2782(T)).

Complete genome sequence of strain 1860, a crenarchaeon of the genus Pyrobaculum able to grow with various electron acceptors.

Strain 1860, a novel member of the genus Pyrobaculum, is a hyperthermophilic organotrophic crenarchaeon growing anaerobically with various electron acceptors. The complete genome sequence reveals genes for several membrane-bound oxidoreductases, the Embden-Meyerhof and Entner-Doudoroff pathways for glucose metabolism, the tricarboxylic acid cycle, the glyoxylate cycle, and the dicarboxylate/4-hydroxybutyrate cycle.

Biodiversity of thermophilic prokaryotes with hydrolytic activities in hot springs of Uzon Caldera, Kamchatka (Russia).

Samples of water from the hot springs of Uzon Caldera with temperatures from 68 to 87 degrees C and pHs of 4.1 to 7.0, supplemented with proteinaceous (albumin, casein, or alpha- or beta-keratin) or carbohydrate (cellulose, carboxymethyl cellulose, chitin, or agarose) biological polymers, were filled with thermal water and incubated at the same sites, with the contents of the tubes freely accessible to the hydrothermal fluid. As a result, several enrichment cultures growing in situ on different polymeric substrates were obtained. Denaturing gradient gel electrophoresis (DGGE) analysis of 16S rRNA gene fragments obtained after PCR with Bacteria-specific primers showed that the bacterial communities developing on carbohydrates included the genera Caldicellulosiruptor and Dictyoglomus and that those developing on proteins contained members of the Thermotogales order. DGGE analysis performed after PCR with Archaea- and Crenarchaeota-specific primers showed that archaea related to uncultured environmental clones, particularly those of the Crenarchaeota phylum, were present in both carbohydrate- and protein-degrading communities. Five isolates obtained from in situ enrichments or corresponding natural samples of water and sediments represented the bacterial genera Dictyoglomus and Caldanaerobacter as well as new archaea of the Crenarchaeota phylum. Thus, in situ enrichment and consequent isolation showed the diversity of thermophilic prokaryotes competing for biopolymers in microbial communities of terrestrial hot springs.