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).

Pelovirga terrestris gen. nov., sp. nov., anaerobic, alkaliphilic, fumarate-, arsenate-, Fe(III)- and sulfur-reducing bacterium isolated from a terrestrial mud volcano.

A novel anaerobic, mesophilic, alkaliphilic, chemoorganotrophic bacterium (strain M08fumT) was isolated from a salsa lake of a terrestrial mud volcano (Taman Peninsula, Russia). Cell of strain M08fumT were Gram-stain-negative, rod-shaped, non-spore forming motile rods. The temperature range for growth was 10-45 °C (optimum at 30 °C). The pH range for growth was 7.0-11.0, with an optimum at pH 8.5-9.0. The isolate was capable of organic acids fermentation and anaerobic respiration with elemental sulfur, Fe(III) and arsenate. The end products of fumarate fermentation were succinate, acetate and CO2. The closest phylogenetic relatives of strain M08fumT were members of the family Geopsychrobacteraceae, class Desulfuromonadia. The genome of strain M08fumT had a size of 3.10 Mb with a DNA G + C content of 53.1% (WGS). Genome analysis revealed the presence of genes involved in fumarate fermentation, arsenate reduction and resistance, sulfur respiration and Fe (III) reduction. Based on the phenotypic, genotypic and phylogenetic characteristics we propose to assign strain M08fumT to a new species of a novel genus Pelovirga terrestris gen. nov., sp. nov. within the family Geopsychrobacteraceae. The type strain of Pelovirga terrestris is M08fumT (=KCTC 15919T = VKM B-3407T). This is the first representative of the class Desulfuromonadia, isolated in pure culture from a mud volcano and the first alkaliphile in the family Geopsychrobacteraceae.

Perlabentimonas gracilis gen. nov., sp. nov., a gliding aerotolerant anaerobe of the order Bacteroidales, isolated from a terrestrial mud volcano.

A novel anaerobic bacterium (strain M08_MBT) was isolated from a terrestrial mud volcano (Taman Peninsula, Russia). Gram-stain-negative cells were straight and slender rods with gliding motility, occasionally forming long filaments. The isolate was mesophilic, slightly halo- and alkaliphilic chemoorganoheterotroph, growing on carbohydrates (starch, dextrin, pectin, glucose, fructose, mannose, maltose, trehalose, lactose, sucrose) and proteinaceous compounds (peptone, tryptone, gelatin, casein and albumin). Strain M08_MBT tolerated 3% oxygen in the gas phase while catalase negative. The dominant cellular fatty acids of strain M08_MBT were C15:0, C15:1 and C13:0 acids. 16S rRNA gene sequence analysis revealed that strain M08_MBT belongs to the order Bacteroidales and only distantly related to other cultivated members of this order (85.12-90.01% 16S rRNA gene similarity). The genome of strain M08_MBT had a size of 4.37 Mb with a DNA G + C content of 43.5 mol% (WGS). The genes involved in gliding motility, proteolysis, central carbon metabolism, and oxygen tolerance were listed in genome annotation. Based on the phenotypic and genotypic characteristics, strain M08_MBT represents a novel species of a novel genus within family Tenuifilaceae, with proposed name Perlabentimonas gracilis gen. nov., sp. nov. The type strain is M08_ MBT (=DSM 110720 T = VKM B-3471 T). This is the first representative of Bacteroidales isolated in pure culture from a mud volcano.

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).

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).