Candidatus Mcinerneyibacterium aminivorans gen. nov., sp. nov., the first representative of the candidate phylum Mcinerneyibacteriota phyl. nov. recovered from a high temperature, high salinity tertiary oil reservoir in north central Oklahoma, USA.

We report on the characterization of a novel genomic assembly (ARYD3) recovered from formation water (17.6% salinity) and crude oil enrichment amended by isolated soy proteins (0.2%), and incubated for 100 days under anaerobic conditions at 50°C. Phylogenetic and phylogenomic analysis demonstrated that the ARYD3 is unaffiliated with all currently described bacterial phyla and candidate phyla, as evident by the low AAI (34.7%), shared gene content (19.4%), and 78.9% 16S rRNA gene sequence similarity to Halothiobacillus neapolitanus, its closest cultured relative. Genomic characterization predicts a slow-growing, non-spore forming, and non-motile Gram-negative rod. Adaptation to high salinity is potentially mediated by the production of the compatible solutes cyclic 2,3-diphosphoglycerate (cDPG), α-glucosylglycerate, as well as the uptake of glycine betaine. Metabolically, the genome encodes primarily aminolytic capabilities for a wide range of amino acids and peptides. Interestingly, evidence of propionate degradation to succinate via methyl-malonyl CoA was identified, suggesting possible capability for syntrophic propionate degradation. Analysis of ARYD3 global distribution patterns identified its occurrence in a very small fraction of Earth Microbiome Project datasets examined (318/27,068), where it consistently represented an extremely rare fraction (maximum 0.28%, average 0.004%) of the overall community. We propose the Candidatus name Mcinerneyibacterium aminivorans gen. nov, sp. nov. for ARYD3T, with the genome serving as the type material for the novel family Mcinerneyibacteriaceae fam. nov., order Mcinerneyibacteriales ord. nov., class Mcinerneyibacteria class nov., and phylum Mcinerneyibacteriota phyl. nov. The type material genome assembly is deposited in GenBank under accession number VSIX00000000.

Description of Biomaibacter acetigenes gen. nov., sp. nov., and proposal of Thermosediminibacterales ord. nov. containing two novel families of Tepidanaerobacteraceae fam. nov. and Thermosediminibacteraceae fam. nov.

A Gram-stain-negative, rod-shaped, chemoorganotrophic and anaerobic bacterium, strain SK-G1T, was isolated from oily sludge sampled at the Shengli oilfield in PR China. Growth occurred with 0-30 g l-1 NaCl, at 40-65 °C and at pH 6.0-8.5. The predominant fatty acids were C14 : 0 and C13 : 0, and the major cellular polar lipids were phosphatidylglycerol and phosphatidylethanolamine. No respiratory quinone was detected. The genomic G+C content was 43.9 mol%. The strain had highest 16S rRNA gene sequence similarity (93.2 % identity) to Tepidanaerobacter syntrophicus DSM 15584T. The phylogenetic, phenotypic and chemotaxonomic data showed that strain SK-G1T (=CCAM 530T=KCTC 15783T=JCM 33158T) represents a novel species of a new genus Biomaibacteracetigenes gen. nov., sp. nov. The results of phylogenetic and phylogenomic analyses indicated that the genera Biomaibacter, Caldanaerovirga, Fervidicola, Tepidanaerobacter, Thermosediminibacter, Thermovenabulum and Thermovoraxformed a clade with high bootstrap support distinguishing to other taxon within the order Thermoanaerobacterales. This clade is proposed as Thermosediminibacterales ord. nov. and includes Tepidanaerobacteraceae fam. nov. and Thermosediminibacteraceae fam. nov. Emended descriptions of the order Thermoanaerobacterales and family Syntrophomonadaceae are also provided.

A metabolic and genomic assessment of sugar fermentation profiles of the thermophilic Thermotogales, Fervidobacterium pennivorans.

A metabolic, genomic and proteomic assessment of Fervidobacterium pennivorans strains was undertaken to clarify the metabolic and genetic capabilities of this Thermotogales species. The type strain Ven5 originally isolated from a hot mud spa in Italy, and a newly isolated strain (DYC) from a hot spring at Ngatamariki, New Zealand, were compared for metabolic and genomic differences. The fermentation profiles of both strains on cellobiose generated similar major end products (acetate, alanine, glutamate, H2, and CO2). The vast majority of end products produced were redox neutral, and carbon balances were in the range of 95-115%. Each strain showed distinct fermentation profiles on sugar substrates. The genome of strain DYC was sequenced and shown to have high sequence similarity and synteny with F. pennivorans Ven5 genome, suggesting they are the same species. The unique genome regions in Ven5, corresponded to genes involved in the Entner-Doudoroff pathway confirming our observation of DYC's inability to utilize gluconate. Genome analysis was able to elucidate pathways involved in production of the observed end-products with the exception of alanine and glutamate synthesis which were resolved with less clarity due to poor sequence identity and missing critical enzymes within the pathway, respectively.

Towards a congruent reclassification and nomenclature of the thermophilic species of the genus Pseudothermotoga within the order Thermotogales.

The phylum Thermotogae gathers thermophilic, hyperthermophic, mesophilic, and thermo-acidophilic anaerobic bacteria that are mostly originated from geothermally heated environments. The metabolic and phenotypic properties harbored by the Thermotogae species questions the evolutionary events driving the emergence of this early branch of the universal tree of life. Recent reshaping of the Thermotogae taxonomy has led to the description of a new genus, Pseudothermotoga, a sister group of the genus Thermotoga within the order Thermotogales. Comparative genomics of both Pseudothermotoga and Thermotoga spp., including 16S-rRNA-based phylogenetic, pan-genomic analysis as well as signature indel conservation, provided evidence that Thermotoga caldifontis and Thermotoga profunda species should be reclassified within the genus Pseudothermotoga and renamed as Pseudothermotoga caldifontis comb. nov. (type strain=AZM44c09T) and Pseudothermotoga profunda comb. nov. (type strain=AZM34c06T), respectively. In addition, based upon whole-genome relatedness indices and DNA-DNA Hybridization results, the reclassification of Pseudothermotoga lettingae and Pseudothermotoga subterranea as latter heterotypic synonyms of Pseudothermotoga elfii is proposed. Finally, potential genetic elements resulting from the distinct evolutionary story of the Thermotoga and Pseudothermotoga clades are discussed.

Pyrosequencing Analysis of Subgingival Microbiota in Distinct Periodontal Conditions.

Subgingival microorganisms are potentially associated with periodontal diseases. However, changes in the subgingival microbiota during the progress of periodontal diseases are poorly understood. In this study, we analyzed bacterial communities in the subgingival paper point samples from 32 Korean individuals with no sign of disease, gingivitis, or periodontitis using 454 FLX Titanium pyrosequencing. A total of 256,113 reads representing 26 phyla, 433 genera, and 1,016 species were detected. Bacteroidetes, Fusobacteria, Synergistetes, and Spirochaetes were the abundant phyla in periodontitis subjects, whereas Firmicutes and Proteobacteria were identified as the dominant phyla in the gingivitis and healthy subjects, respectively. Although high levels of Porphyromonas, Fusobacterium, Fretibacterium, Rothia, Filifactor, and Treponema genera were observed in the periodontitis subjects, Streptococcus, Capnocytophaga, Leptotrichia, and Haemophilus genera were found at high frequency in the gingivitis subjects. Species including Porphyromonas gingivalis, Fusobacterium nucleatum, and Fretibacterium fastidiosum were significantly increased in periodontitis subjects. On the other hand, Streptococcus pseudopneumoniae, Haemophilus parainfluenzae, and Leptotrichia hongkongensis were preferentially observed in the gingivitis subjects. Intriguingly, the halophile Halomonas hamiltonii was revealed as a predominant species in the healthy subjects. Based on Fast UniFrac analysis, distinctive bacterial clusters were classified for the healthy, gingivitis, and periodontitis state. The current findings might be useful for understanding the pathogenesis, diagnosis, and treatment of periodontal diseases.

Caloranaerobacter ferrireducens sp. nov., an anaerobic, thermophilic, iron (III)-reducing bacterium isolated from deep-sea hydrothermal sulfide deposits.

A thermophilic, anaerobic, iron-reducing bacterium (strain DY22619T) was isolated from a sulfide sample collected from an East Pacific Ocean hydrothermal field at a depth of 2901 m. Cells were Gram-stain-negative, motile rods (2-10 µm in length, 0.5 µm in width) with multiple peritrichous flagella. The strain grew at 40-70 °C inclusive (optimum 60 °C), at pH 4.5-8.5 inclusive (optimum pH 7.0) and with sea salts concentrations of 1-10 % (w/v) (optimum 3 % sea salts) and NaCl concentrations of 1.5-5.0 % (w/v) (optimum 2.5 % NaCl). Under optimal growth conditions, the generation time was around 55 min. The isolate was an obligate chemoorganoheterotroph, utilizing complex organic compounds, amino acids, carbohydrates and organic acids including peptone, tryptone, beef extract, yeast extract, alanine, glutamate, methionine, threonine, fructose, mannose, galactose, glucose, palatinose, rhamnose, turanose, gentiobiose, xylose, sorbose, pyruvate, tartaric acid, α-ketobutyric acid, α-ketovaleric acid, galacturonic acid and glucosaminic acid. Strain DY22619T was strictly anaerobic and facultatively dependent on various forms of Fe(III) as an electron acceptor: insoluble forms and soluble forms. It did not reduce sulfite, sulfate, thiosulfate or nitrate. The genomic DNA G+C content was 29.0 mol%. Phylogenetic 16S rRNA gene sequence analyses revealed that the closest relative of strain DY22619T was Caloranaerobacter azorensis MV1087T, sharing 97.41 % 16S rRNA gene sequence similarity. On the basis of physiological distinctness and phylogenetic distance, the isolate is considered to represent a novel species of the genus Caloranaerobacter, for which the name Caloranaerobacterhttp://dx.doi.org/10.1601/nm.4081ferrireducens sp. nov. is proposed. The type strain is DY22619T ( = JCM 19467T = DSM 27799T = MCCC1A06455T).

A pipeline for completing bacterial genomes using in silico and wet lab approaches.

BACKGROUND: Despite the large volume of genome sequencing data produced by next-generation sequencing technologies and the highly sophisticated software dedicated to handling these types of data, gaps are commonly found in draft genome assemblies. The existence of gaps compromises our ability to take full advantage of the genome data. This study aims to identify a practical approach for biologists to complete their own genome assemblies using commonly available tools and resources. RESULTS: A pipeline was developed to assemble complete genomes primarily from the next generation sequencing (NGS) data. The input of the pipeline is paired-end Illumina sequence reads, and the output is a high quality complete genome sequence. The pipeline alternates the employment of computational and biological methods in seven steps. It combines the strengths of de novo assembly, reference-based assembly, customized programming, public databases utilization, and wet lab experimentation. The application of the pipeline is demonstrated by the completion of a bacterial genome, Thermotoga sp. strain RQ7, a hydrogen-producing strain. CONCLUSIONS: The developed pipeline provides an example of effective integration of computational and biological principles. It highlights the complementary roles that in silico and wet lab methodologies play in bioinformatical studies. The constituting principles and methods are applicable to similar studies on both prokaryotic and eukaryotic genomes.

Anaerosolibacter carboniphilus gen. nov., sp. nov., a strictly anaerobic iron-reducing bacterium isolated from coal-contaminated soil.

A strictly anaerobic, mesophilic, iron-reducing bacterial strain, IRF19(T), was isolated from coal-contaminated soil in the Republic of Korea. IRF19(T) cells were straight, rod-shaped, Gram-staining-negative and motile by means of flagella. The optimum pH and temperature for their growth were determined to be pH 7.5-8.0 and 40 °C, while the optimum range was pH 6.5-10.0 and 20-45 °C, respectively. Strain IRF19(T) did not require NaCl for growth but it tolerated up to 2% (w/v). Growth was observed with yeast extract, D-glucose, D-fructose, D-ribose, D-mannitol, D-mannose, L-serine, L-alanine and L-isoleucine. Fe(III), elemental sulfur, thiosulfate and sulfate were used as electron acceptors. Phylogenetic analysis based on the 16S rRNA gene sequences indicated that strain IRF19(T) is affiliated to the family Clostridiaceae and is most closely related to Salimesophilobacter vulgaris Zn2(T) (93.5% similarity), Geosporobacter subterraneus VNs68(T) (93.2%) and Thermotalea metallivorans B2-1(T) (92.3%). The major cellular fatty acids of strain IRF19(T) were C14 : 0, iso-C15 : 0 and C16 : 0, and the profile was distinct from those of the closely related species. The major respiratory quinone of strain IRF19(T) was menaquinone MK-5 (V-H2). The main polar lipids were diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol, an unknown phospholipid and two unknown polar lipids. The G+C content of the genomic DNA of strain IRF19(T) was determined to be 37.4 mol%. On the basis of phenotypic, chemotaxonomic and phylogenetic results, strain IRF19(T) is considered to represent a novel species of a novel genus of the family Clostridiaceae , for which we propose the name Anaerosolibacter carboniphilus gen. nov., sp. nov., with the type strain IRF19(T) ( =KCTC 15396(T) =JCM 19988(T)).

Thermosipho activus sp. nov., a thermophilic, anaerobic, hydrolytic bacterium isolated from a deep-sea sample.

A novel obligately anaerobic, extremely thermophilic, organotrophic bacterium, strain Rift-s3(T), was isolated from a deep-sea sample containing Riftia pachyptila sheath from Guaymas Basin, Gulf of California. Cells of the novel isolate were rods, 0.3-0.8 µm in width and 1.5-10 µm in length, surrounded by a sheath-like structure (toga). Strain Rift-s3(T) grew at temperatures ranging from 44 to 75 °C, at pH 5.5 to 8.0, and with NaCl concentrations of 3 to 60 g l(-1). Under optimum conditions (65 °C, pH 6.0, NaCl 25 g l(-1)), the doubling time was 30 min. The isolate was able to ferment mono-, oligo- and polysaccharides including cellulose, chitin, xylan and pectin, and proteins including ß-keratins, casein and gelatin. Acetate, hydrogen and carbon dioxide were the main products of glucose fermentation. The G+C content of the DNA was 30 mol%. Phylogenetic analysis of 16S rRNA gene sequences showed the affiliation of strain Rift-s3(T) with the genus Thermosipho, with Thermosipho atlanticus Ob7(T) as the closest relative (96.5 % 16S rRNA gene sequence similarity). Based on the phylogenetic analysis and physiological properties of the novel isolate we propose a novel species of the genus Thermosipho, Thermosipho activus sp. nov., with Rift-s3(T) ( = DSM 26467(T) = VKM B-2803(T)) as the type strain.

Ercella succinigenes gen. nov., sp. nov., an anaerobic succinate-producing bacterium.

A novel anaerobic succinate-producing bacterium, strain ZWB(T), was isolated from sludge collected from a biogas desulfurization bioreactor (Eerbeek, the Netherlands). Cells were non-spore-forming, motile, slightly curved rods (0.4-0.5 µm in diameter and 2-3 µm in length), and stained Gram-negative. The temperature range for growth was 25-40 °C, with an optimum at 37 °C. The pH range for growth was 7.0-9.0, with an optimum at pH 7.5. Strain ZWB(T) was able to ferment glycerol and several carbohydrates mainly to H2, succinate and acetate. Sulfur and fumarate could be used as electron acceptors by strain ZWB(T). The G+C content of the genomic DNA was 37.6 mol%. The most abundant fatty acids were iso-C14 : 0 and iso-C16 : 0 DMA. On the basis of 16S rRNA gene sequence similarity, strain ZWB(T) belongs to the family Ruminococcaceae and it is distantly related to Saccharofermentans acetigenes JCM 14006(T) (92.1%). Based on the physiological features and phylogenetic analysis, strain ZWB(T) represents a novel species of a new genus, for which the name Ercella succinigenes gen. nov., sp. nov. is proposed. The type strain of Ercella succinigenes is ZWB(T) ( = DSM 27333(T) = JCM 19283(T)).

Petrotoga japonica sp. nov., a thermophilic, fermentative bacterium isolated from Yabase Oilfield in Japan.

A gram-negative, motile, fermentative, thermophilic bacterium, designated AR80(T), was isolated from a high-temperature oil reservoir in Yabase Oilfield in Akita, Japan. Cells were rod-shaped, motile by means of polar flagella, and formed circular, convex, white colonies. The strain grew at 40-65 °C (optimum 60 °C), 0.5-9 % (w/v) NaCl (optimum 0.5-1 %), pH 6-9 (optimum pH 7.5), and elemental sulfur or thiosulfate serves as terminal electron acceptor. Phylogenetic analysis of 16S rRNA gene sequences indicated that strain AR80(T) belonged to the genus Petrotoga and shared approximately 94.5 % sequence similarity with the type species of this genus. The G + C content of genomic DNA was 32.4 mol% while the value of DNA-DNA hybridization between the closest relative species Petrotoga miotherma and AR80(T) was 58.1 %. The major cellular fatty acids of strain AR80(T) consisted of 18:1 w9c, 16:0, and 16:1 w9c. Based on genetic and phenotypic properties, strain AR80(T) was different with other identified Petrotoga species and represents as a novel species, for which the name Petrotoga japonica sp. nov. is proposed. The type strain is AR80(T) (=NBRC 108752(T) = KCTC 15103(T) = HUT 8122(T)).

Thermotoga profunda sp. nov. and Thermotoga caldifontis sp. nov., anaerobic thermophilic bacteria isolated from terrestrial hot springs.

Two thermophilic, strictly anaerobic, Gram-negative bacteria, designated strains AZM34c06(T) and AZM44c09(T), were isolated from terrestrial hot springs in Japan. The optimum growth conditions for strain AZM34c06(T) were 60 °C, pH 7.4 and 0% additional NaCl, and those for strain AZM44c09(T) were 70 °C, pH 7.4 and 0% additional NaCl. Complete genome sequencing was performed for both strains, revealing genome sizes of 2.19 Mbp (AZM34c06(T)) and 2.01 Mbp (AZM44c09(T)). Phylogenetic analyses based on 16S rRNA gene sequences and the concatenated predicted amino acid sequences of 33 ribosomal proteins showed that both strains belonged to the genus Thermotoga. The closest relatives of strains AZM34c06(T) and AZM44c09(T) were the type strains of Thermotoga lettingae (96.0% similarity based on the 16S rRNA gene and 84.1% similarity based on ribosomal proteins) and Thermotoga hypogea (98.6 and 92.7% similarity), respectively. Using blast, the average nucleotide identity was 70.4-70.5% when comparing strain AZM34c06(T) and T. lettingae TMO(T) and 76.6% when comparing strain AZM44c09(T) and T. hypogea NBRC 106472(T). Both values are far below the 95% threshold value for species delineation. In view of these data, we propose the inclusion of the two isolates in the genus Thermotoga within two novel species, Thermotoga profunda sp. nov. (type strain AZM34c06(T) = NBRC 106115(T) = DSM 23275(T)) and Thermotoga caldifontis sp. nov. (type strain AZM44c09(T) = NBRC 106116(T) = DSM 23272(T)).

Lactivibrio alcoholicus gen. nov., sp. nov., an anaerobic, mesophilic, lactate-, alcohol-, carbohydrate- and amino-acid-degrading bacterium in the phylum Synergistetes.

A mesophilic, obligately anaerobic, lactate-, alcohol-, carbohydrate- and amino-acid- degrading bacterium, designated strain 7WAY-8-7(T), was isolated from an upflow anaerobic sludge blanket reactor treating high-strength organic wastewater from isomerized sugar production processes. Cells of strain 7WAY-8-7(T) were motile, curved rods (0.7-1.0×5.0-8.0 µm). Spore formation was not observed. The strain grew optimally at 37 °C (range for growth was 25-40 °C) and pH 7.0 (pH 6.0-7.5), and could grow fermentatively on yeast extract, glucose, ribose, xylose, malate, tryptone, pyruvate, fumarate, Casamino acids, serine and cysteine. The main end-products of glucose fermentation were acetate and hydrogen. In co-culture with the hydrogenotrophic methanogen Methanospirillum hungatei DSM 864(T), strain 7WAY-8-7(T) could utilize lactate, glycerol, ethanol, 1-propanol, 1-butanol, L-glutamate, alanine, leucine, isoleucine, valine, histidine, asparagine, glutamine, arginine, lysine, threonine, 2-oxoglutarate, aspartate and methionine. A Stickland reaction was not observed with some pairs of amino acids. Yeast extract was required for growth. Nitrate, sulfate, thiosulfate, elemental sulfur, sulfite and Fe (III) were not used as terminal electron acceptors. The G+C content of the genomic DNA was 61.4 mol%. 16S rRNA gene sequence analysis revealed that the isolate belongs to the uncultured environmental clone clade (called 'PD-UASB-13' in the Greengenes database) in the bacterial phylum Synergistetes, showing less than 90% sequence similarity with closely related described species such as Aminivibrio pyruvatiphilus and Aminobacterium colombiense (89.7% and 88.7%, respectively). The major cellular fatty acids were iso-C(13 : 0), iso-C(15 : 0), anteiso-C(15 : 0), C(18 : 1), C(19 : 1), C(20 : 1) and C(21 : 1). A novel genus and species, Lactivibrio alcoholicus gen. nov., sp. nov. is proposed to accommodate strain 7WAY-8-7(T) ( = JCM 17151(T) = DSM 24196(T) = CGMCC 1.5159(T)).

Youngiibacter fragilis gen. nov., sp. nov., isolated from natural gas production-water and reclassification of Acetivibrio multivorans as Youngiibacter multivorans comb. nov.

A taxonomic study employing a polyphasic approach was performed on a novel anaerobic bacterium isolated from natural gas production-water. The bacterium stained Gram-negative and consisted of non-motile, non-spore-forming, rod-shaped cells. Products of glucose or starch fermentation were ethanol, CO2, formate, acetate and H2. The predominant fatty acids were C16 : 0 ALDE and summed feature 3 comprising C16 : 1ω7c and/or C16 : 1ω6c. The DNA G+C content was 45.5 mol%. 16S rRNA gene sequence analysis demonstrated that the nearest phylogenetic neighbours of the novel strain were Acetivibrio multivorans DSM 6139(T) (98.5 %) and Proteiniclasticum ruminis JCM 14817(T) (95.4 %). The DNA-DNA hybridization value between the novel organism and Acetivibrio multivorans PeC1 DSM 6139(T) was determined to be only 30.2 %, demonstrating the separateness of the two species. Based on phylogenetic, phenotypic and chemotaxonomic evidence that clearly distinguished strain 232.1(T) from Proteiniclasticum ruminis and other close relatives, it is proposed that the novel isolate be classified as representing a novel species of a new genus within the family Clostridiaceae, Youngiibacter fragilis gen. nov., sp. nov. The type strain of the type species is 232.1(T) ( = ATCC BAA-2257(T) = DSM 24749(T)). In addition, Acetivibrio multivorans is proposed to be reclassified as Youngiibacter multivorans comb. nov.

Reconstruction of ancestral 16S rRNA reveals mutation bias in the evolution of optimal growth temperature in the Thermotogae phylum.

Optimal growth temperature is a complex trait involving many cellular components, and its physiology is not yet fully understood. Evolution of continuous characters, such as optimal growth temperature, is often modeled as a one-dimensional random walk, but such a model may be an oversimplification given the complex processes underlying the evolution of continuous characters. Recent articles have used ancestral sequence reconstruction to infer the optimal growth temperature of ancient organisms from the guanine and cytosine content of the stem regions of ribosomal RNA, allowing inferences about the evolution of optimal growth temperature. Here, we investigate the optimal growth temperature of the bacterial phylum Thermotogae. Ancestral sequence reconstruction using a nonhomogeneous model was used to reconstruct the stem guanine and cytosine content of 16S rRNA sequences. We compare this sequence reconstruction method with other ancestral character reconstruction methods, and show that sequence reconstruction generates smaller confidence intervals and different ancestral values than other reconstruction methods. Unbiased random walk simulation indicates that the lower temperature members of the Thermotogales have been under directional selection; however, when a simulation is performed that takes possible mutations into account, it is the high temperature lineages that are, in fact, under directional selection. We find that the evolution of Thermotogales optimal growth temperatures is best fit by a biased random walk model. These findings suggest that it may be easier to evolve from a high optimal growth temperature to a lower one than vice versa.

Mesoaciditoga lauensis gen. nov., sp. nov., a moderately thermoacidophilic member of the order Thermotogales from a deep-sea hydrothermal vent.

A novel moderately thermophilic, heterotrophic bacterium was isolated from a deep-sea hydrothermal vent deposit from the Mariner field along the Eastern Lau Spreading Center of the south-western Pacific Ocean. Cells were short motile rods (about 0.4×0.8 µm) that occurred singly or in pairs and were surrounded by a sheath-like membrane or 'toga'. The cells grew between 45 and 65 °C (optimum 57-60 °C) and at pH 4.1-6.0 (optimum pH 5.5-5.7) and grew optimally at 3 % (w/v) NaCl. The isolate grew on a range of carbon and proteinaceous substrates and reduced sulfur. The G+C content of the DNA was about 45 mol%. Phylogenetic analysis of the 16S rRNA gene sequence placed the new isolate as a deeply diverging lineage within the order Thermotogales. Based on the physiological, morphological and phylogenetic data, the isolate represents a novel species of a new genus with the proposed name Mesoaciditoga lauensis gen. nov., sp. nov. The type strain of Mesoaciditoga lauensis is cd-1655R(T) ( = DSM 25116(T) = OCM 1212(T)).

Mesotoga infera sp. nov., a mesophilic member of the order Thermotogales, isolated from an underground gas storage aquifer.

Strain VNs100(T), a novel mesophilic, anaerobic, rod-coccoid-shaped bacterium, having a sheath-like outer structure (toga), was isolated from a water sample collected in the area of an underground gas storage aquifer. It was non-motile with cells appearing singly (2-4 µm long × 1-2 µm wide), in pairs or as long chains and stained Gram-negative. Strain VNs100(T) was heterotrophic, able to use arabinose, cellobiose, fructose, galactose, glucose, lactose, lactate, mannose, maltose, raffinose, ribose, sucrose and xylose as energy sources only in the presence of elemental sulfur as terminal electron acceptor. Acetate, CO2 and sulfide were the end products of sugar metabolism. Hydrogen was not detected. Elemental sulfur, but not thiosulfate, sulfate or sulfite, were reduced to sulfide. Strain VNs100(T) grew at temperatures between 30 and 50 °C (optimum 45 °C), at pH values between 6.2 and 7.9 (optimum 7.3-7.5) and at NaCl concentrations between 0 and 15 g l(-1) (optimum 2 g l(-1)). The DNA G+C content was 47.5 mol%. The main cellular fatty acid was C16 : 0. Phylogenetic analysis of the small subunit rRNA gene sequence indicated that strain VNs100(T) had as its closest relatives 'Mesotoga sulfurireducens' (97.1 % similarity) and Mesotoga prima (similarity of 97.1 % and 97.7 % with each of its two genes, respectively) within the order Thermotogales. Hybridization between strain VNS100(T) and 'M. sulfurireducens' and between strain VNS100(T) and M. prima showed 12.9 % and 20.6 % relatedness, respectively. Based on phenotypic, phylogenetic and taxonomic characteristics, strain VNs100(T) is proposed as a representative of a novel species of the genus Mesotoga in the family Thermotogaceae, order Thermotogales. The name Mesotoga infera sp. nov. is proposed. The type strain is VNs100(T) (= DSM 25546(T) = JCM 18154(T)).

Thermophagus xiamenensis gen. nov., sp. nov., a moderately thermophilic and strictly anaerobic bacterium isolated from hot spring sediment.

A moderately thermophilic and strictly anaerobic bacterium, designated HS1(T), was isolated from offshore hot spring sediment in Xiamen, China. Cells were Gram-negative, catalase-positive, oxidase-negative, slender and flexible rods without flagella. The strain could grow at 35-55 °C (optimum at 50 °C) and in 1-8 % NaCl (w/v; optimum 2-4 %). Phylogenetic analysis based on 16S rRNA gene sequences showed that strain HS1(T) was affiliated with the family Marinilabiliaceae and shared a distant relationship with the previously described genera. The isolate was most closely related to Anaerophaga thermohalophila Fru22(T) with 16S rRNA gene sequence similarity of 92.4 %, followed by the other members of the family Marinilabiliaceae with 88.7-91.1 % similarity. The dominant cellular fatty acids were iso-C(15 : 0) and anteiso-C(15 : 0). The predominant quinone was MK-7. The major polar lipids were phosphatidylethanolamine (PE) and an unknown polar lipid. The genomic DNA G+C content was 38.7 mol%. Besides the phylogenetically distant relationship, strain HS1(T) was obviously distinguished from the most closely related genera in several phenotypic properties including colony colour and pigment production, optimal temperature, optimal NaCl, relation to O(2), bicarbonate/carbonate requirement, catalase activity, nitrate reduction, fermentation products and cellular fatty acid profile. Based on the phenotypic and phylogenetic data, strain HS1(T) represents a novel species of a new genus, for which the name Thermophagus xiamenensis gen. nov., sp. nov. is proposed. The type strain of the type species is HS1(T) (= DSM 19012(T) = CGMCCC 1.5071(T)).

Cloacibacillus porcorum sp. nov., a mucin-degrading bacterium from the swine intestinal tract and emended description of the genus Cloacibacillus.

A novel anaerobic, mesophilic, amino-acid-fermenting bacterium, designated strain CL-84(T), was isolated from the swine intestinal tract on mucin-based media. Cells were curved rods (0.8-1.2 × 3.5-5.0 µm), stained Gram-negative and were non-motile with no evidence of spores. Strain CL-84(T) produced acetate, propionate, formate and butyrate as the end products of metabolism when grown on serine. Optimum growth occurred at 39 °C and pH 6.5. The major cellular fatty acids were iso-C15:0, iso-C15:0 3-OH, iso-C17:0 and C16:0, distinguishing strain CL-84(T) from closely related species. The DNA G+C content of strain CL-84(T) was 55.1 mol%. 16S rRNA gene sequence analysis showed that strain CL-84(T) shared 90-95% similarity with characterized genera within the phylum Synergistetes, family Synergistaceae. Phylogenetic analysis showed that strain CL-84(T) was related to, but distinct from, Cloacibacillus evryensis. Based on these findings, we propose that strain CL-84(T) represents a novel species of the genus Cloacibacillus. We further propose the name Cloacibacillus porcorum sp. nov. be designated for this species. The type strain is CL-84(T) (=DSM 25858(T)=CCUG 62631(T)). An emended description of the genus Cloacibacillus is provided.

Mesotoga prima gen. nov., sp. nov., the first described mesophilic species of the Thermotogales.

A novel mesophilic member of the Thermotogales, strain MesG1.Ag.4.2, was isolated from sediments from Baltimore Harbor, MD, USA. The strain grew optimally at 37 °C with a doubling time of 16.5 h on xylose. Carbohydrates and proteinaceous compounds supported growth and pentoses were preferred over hexoses. The strain was strictly anaerobic and growth was slightly stimulated by thiosulfate, sulfite, and elemental sulfur. The G + C content of its genomic DNA was 45.3 mol%. Strain MesG1.Ag.4.2 and Kosmotoga olearia lipids were analyzed. Strain MesG1.Ag.4.2 contained no long-chain dicarboxylic acids and its major phospholipid was lyso-phosphatidylserine. Long-chain dicarboxylic acids were found in K. olearia and its major phospholipid was cardiolipin, a lipid not yet reported in Thermotogales species. Phylogenetic analyses of its two 16S rRNA genes placed strain MesG1.Ag.4.2 within the bacterial order Thermotogales. Based on the phylogenetic analyses and its low optimal growth temperature, it is proposed that the strain represents a novel species of a new genus within the family Thermotogaceae, order Thermotogales. The name Mesotoga prima gen. nov., sp. nov. is proposed. The type strain of M. prima is MesG1.Ag.4.2 (= DSM 24739 = ATCC BAA-2239).