Miho Watanabe

Bio: Miho Watanabe is an academic researcher from Hokkaido University. The author has contributed to research in topics: Gene & Genome. The author has an hindex of 8, co-authored 33 publications receiving 169 citations. Previous affiliations of Miho Watanabe include Akita Prefectural University & Japan Society for the Promotion of Science.

Review of Desulfotomaculum species and proposal of the genera Desulfallas gen. nov., Desulfofundulus gen. nov., Desulfofarcimen gen. nov. and Desulfohalotomaculum gen. nov.

Abstract: The genus Desulfotomaculum is a heterogeneous group of spore-forming sulfate-reducing bacteria. The type species of the genus is Desulfotomaculum nigrificans (Approved Lists 1980) emend. Visser et al. 2014. The results of phylogenetic analysis demonstrated that the genus Desulfotomaculum already has lost the clustering monophyly and was segregated into some distinct groups with low sequence similarity. Major features of the type strains in these groups were compared, and four novel genera, Desulfallas gen. nov., Desulfofundulus gen. nov., Desulfofarcimen gen. nov. and Desulfohalotomaculum gen. nov. were proposed to accommodate species transferred from the genus Desulfotomaculum .

Desulfatitalea tepidiphila gen. nov., sp. nov., a sulfate-reducing bacterium isolated from tidal flat sediment.

Abstract: A novel sulfate-reducing bacterium, strain S28bFT, was isolated from tidal flat sediment from Tokyo Bay, Japan. Cells of strain S28bFT were rod-shaped (0.5–0.6×1.7–3.8 µm), motile and Gram-stain-negative. For growth, the optimum pH was pH 6.8–7.3 and the optimum temperature was 34–42 °C. Strain S28bFT used sulfate and thiosulfate as electron acceptors, but not nitrate. The G+C content of the genomic DNA was 56.6 mol%. The fatty acid profile of strain S28bFT was characterized by the presence of anteiso-C15 : 0 and C16 : 0 as the major components. Phylogenetic analyses based on genes for 16S rRNA, the alpha subunit of dissimilatory sulfite reductase (dsrA) and adenosine-5′-phosphosulfate reductase (aprA) revealed that the isolated strain belonged to the class Deltaproteobacteria . Its closest relative was Desulfosarcina cetonica DSM 7267T with a 16S rRNA gene sequence similarity of 93.3 %. Two other strains, S28OL1 and S28OL2 were also isolated from the same sediment. These strains were closely related to S28bFT with 16S rRNA gene sequence similarities of 99 %, and the same physiological characteristics were shared with strain S28bFT. On the basis of phylogenetic and phenotypic characterization, a novel species in a new genus, Desulfatitalea tepidiphila gen. nov., sp. nov., is proposed to accommodate the strains obtained in this study. The type strain is S28bFT ( = NBRC 107166T = DSM 23472T).

Desulfosarcina widdelii sp. nov. and Desulfosarcina alkanivorans sp. nov., hydrocarbon-degrading sulfate-reducing bacteria isolated from marine sediment and emended description of the genus Desulfosarcina.

Abstract: In previous studies, two hydrocarbon-degrading sulfate-reducing bacteria, strains PP31T and PL12T, were obtained from oil-polluted marine sediments of Shuaiba, Kuwait. They had been reported as organisms capable of anaerobic degradation of p-xylene and n-alkanes, respectively. The 16S rRNA gene sequence of strain PP31T showed 98.8 % sequence similarities to that of Desulfosarcina variabilis'Montpellier'T. Strains PL12T had 97.8 % of sequence similarity to Desulfosarcina ovata oXys1T. They both have been partially characterized, but not been validly published as new species of the genus Desulfosarcina. In this study, additional characterizations of these strains were made to describe them as two new species of the genus Desulfosarcina. Major cellular fatty acids of strain PP31T were C15 : 0 (25.9 %) and anteiso-C15 : 0 (22.3 %), whereas those of strain PL12T were C15 : 0 (21.3 %), C16 : 0 (17.8 %) and anteiso-15 : 0 (11.6 %). The phylogenetic tree based on 16S rRNA gene revealed that these isolates should not be classified as any of the known species in the genus Desulfosarcina. On the basis of phenotypic and phylogenetic analyses, these two sulfate reducers are proposed to form two novel species of the genus Desulfosarcina : Desulfosarcina widdelii sp. nov. (PP31T=JCM 31729T=DSM 103921T) and Desulfosarcina alkanivorans sp. nov. (PL12T=JCM 31728T=DSM 103901T). In addition, emended description of the genus Desulfosarcina is presented in this study.

Hymenobacter nivis sp. nov., isolated from red snow in Antarctica.

Abstract: A novel aerobic bacterial strain, P3T, was isolated from a red snow obtained from Antarctica. Cells of strain P3T were rod-shaped, non-motile, catalase-negative, oxidase-positive and Gram-stain-negative. Growth was observed at temperatures ranging from 0 to 25 °C, with optimum growth at 15 °C. The pH range for growth was pH 5.3–7.8. The G+C content of the genomic DNA was 55.0 mol%. The major components in the fatty acid profile were iso-C15 : 0, summed feature 4 (iso-C17 : 1 I and/or anteiso-C17 : 1 B), anteiso-C15 : 0 and summed feature 3 (iso-C16 : 1ω7c and/or iso-C16 : 1ω6c). The predominant isoprenoid quinone was MK-7. Phylogenetic analysis based on the 16S rRNA gene sequence indicated that the novel isolate was a member of the genus Hymenobacter , and the strain showed highest sequence similarity (94 %) with H.ymenpbacter glaciei VUG-A130T, Hymenobacter . soli PB17T and Hymenobacter . antarcticus VUG-A42aaT. On the basis of phylogenetic and phenotypic properties strain P3T represents a novel species of the genus Hymenobacter (for which the name Hymenobacter nivis sp. nov. is proposed. The types strain is P3T (=DSM 101755T=NBRC 111535T).

Limnochorda pilosa gen. nov., sp. nov., a moderately thermophilic, facultatively anaerobic, pleomorphic bacterium and proposal of Limnochordaceae fam. nov., Limnochordales ord. nov. and Limnochordia classis nov. in the phylum Firmicutes.

Abstract: A novel facultatively anaerobic bacterium, strain HC45T, was isolated from sediment of a brackish meromictic lake in Japan, Lake Harutori. Cells were pleomorphic, and filamentous bodies were 5–100 μm in length. For growth, the optimum pH was 7.0 and the optimum temperature was 45–50 °C. The G+C content of the genomic DNA was 71 mol%. iso-C15 : 0 and anteiso-C15 : 0 were the major components in the cellular fatty acid profile. The predominant respiratory quinone was MK-7. Strain HC45T shared very low 16S rRNA gene sequence similarity with cultivated strains ( ≤ 85 %). Phylogenetic analysis based on 16S rRNA gene sequences revealed that the isolate was distantly related to members of the family Symbiobacteriaceae and family XVII Incertae Sedis in the class Clostridia, and they formed a cluster separate from canonical species of the phylum Firmicutes. These results indicated that strain HC45T should not be placed in any existing class of the phylum Firmicutes. On the basis of phylogenetic and phenotypic characterization, Limnochorda pilosa gen. nov., sp. nov. is proposed with HC45T ( = NBRC 110152T = DSM 28787T) as the type strain, as the first representative of novel taxa, Limnochordales ord. nov., Limnochordaceae fam. nov. in Limnochordia classis. nov.

SPAdes, a new genome assembly algorithm and its applications to single-cell sequencing ( 7th Annual SFAF Meeting, 2012)

Abstract: The lion's share of bacteria in various environments cannot be cloned in the laboratory and thus cannot be sequenced using existing technologies. A major goal of single-cell genomics is to complement gene-centric metagenomic data with whole-genome assemblies of uncultivated organisms. Assembly of single-cell data is challenging because of highly non-uniform read coverage as well as elevated levels of sequencing errors and chimeric reads. We describe SPAdes, a new assembler for both single-cell and standard (multicell) assembly, and demonstrate that it improves on the recently released E+V-SC assembler (specialized for single-cell data) and on popular assemblers Velvet and SoapDeNovo (for multicell data). SPAdes generates single-cell assemblies, providing information about genomes of uncultivatable bacteria that vastly exceeds what may be obtained via traditional metagenomics studies. SPAdes is available online ( http://bioinf.spbau.ru/spades ). It is distributed as open source software.

Proposal to reclassify the proteobacterial classes Deltaproteobacteria and Oligoflexia, and the phylum Thermodesulfobacteria into four phyla reflecting major functional capabilities

Abstract: The class Deltaproteobacteria comprises an ecologically and metabolically diverse group of bacteria best known for dissimilatory sulphate reduction and predatory behaviour. Although this lineage is the fourth described class of the phylum Proteobacteria, it rarely affiliates with other proteobacterial classes and is frequently not recovered as a monophyletic unit in phylogenetic analyses. Indeed, one branch of the class Deltaproteobacteria encompassing Bdellovibrio-like predators was recently reclassified into a separate proteobacterial class, the Oligoflexia. Here we systematically explore the phylogeny of taxa currently assigned to these classes using 120 conserved single-copy marker genes as well as rRNA genes. The overwhelming majority of markers reject the inclusion of the classes Deltaproteobacteria and Oligoflexia in the phylum Proteobacteria. Instead, the great majority of currently recognized members of the class Deltaproteobacteria are better classified into four novel phylum-level lineages. We propose the names Desulfobacterota phyl. nov. and Myxococcota phyl. nov. for two of these phyla, based on the oldest validly published names in each lineage, and retain the placeholder name SAR324 for the third phylum pending formal description of type material. Members of the class Oligoflexia represent a separate phylum for which we propose the name Bdellovibrionota phyl. nov. based on priority in the literature and general recognition of the genus Bdellovibrio. Desulfobacterota phyl. nov. includes the taxa previously classified in the phylum Thermodesulfobacteria, and these reclassifications imply that the ability of sulphate reduction was vertically inherited in the Thermodesulfobacteria rather than laterally acquired as previously inferred. Our analysis also indicates the independent acquisition of predatory behaviour in the phyla Myxococcota and Bdellovibrionota, which is consistent with their distinct modes of action. This work represents a stable reclassification of one of the most taxonomically challenging areas of the bacterial tree and provides a robust framework for future ecological and systematic studies.

Metabolic Capabilities of Microorganisms Involved in and Associated with the Anaerobic Oxidation of Methane.

Abstract: In marine sediments the anaerobic oxidation of methane with sulfate as electron acceptor (AOM) is responsible for the removal of a major part of the greenhouse gas methane. AOM is performed by consortia of anaerobic methane-oxidizing archaea (ANME) and their specific partner bacteria. The physiology of these organisms is poorly understood, which is due to their slow growth with doubling times in the order of months and the phylogenetic diversity in natural and in vitro AOM enrichments. Here we study sediment-free long-term AOM enrichments that were cultivated from seep sediments sampled off the Italian Island Elba (20°C; hereon called E20) and from hot vents of the Guaymas Basin, Gulf of California, cultivated at 37°C (G37) or at 50°C (G50). These enrichments were dominated by consortia of ANME-2 archaea and Seep-SRB2 partner bacteria (E20) or by ANME-1, forming consortia with Seep-SRB2 bacteria (G37) or with bacteria of the HotSeep-1 cluster (G50). We investigate lipid membrane compositions as possible factors for the different temperature affinities of the different ANME clades and show autotrophy as characteristic feature for both ANME clades and their partner bacteria. Although in the absence of additional substrates methane formation was not observed, methanogenesis from methylated substrates (methanol and methylamine) could be quickly stimulated in the E20 and the G37 enrichment. Responsible for methanogenesis are archaea from the genus Methanohalophilus and Methanococcoides, which are minor community members during AOM (1 to 7‰ of archaeal 16S rRNA gene amplicons). In the same two cultures also sulfur disproportionation could be quickly stimulated by addition of zero-valent colloidal sulfur. The isolated partner bacteria are likewise minor community members (1 to 9‰ of bacterial 16S rRNA gene amplicons, whereas the dominant partner bacteria (Seep-SRB1a, Seep-SRB2 or HotSeep-1) did not grow on elemental sulfur. Our results support a functioning of AOM as syntrophic interaction of obligate methanotrophic archaea that transfer non-molecular reducing equivalents (i.e. via direct interspecies electron transfer) to obligate sulfate-reducing partner bacteria. Additional katabolic processes in these enrichments but also in sulfate methane interfaces are likely performed by minor community members.

Sulfurifustis variabilis gen. nov., sp nov., a sulfur oxidizer isolated from a lake, and proposal of Acidiferrobacteraceae fam. nov and Acidiferrobacterales ord. nov.

Abstract: A novel autotrophic bacterium, strain skN76T, was isolated from sediment of a lake in Japan. As sole electron donor to support chemolithoautotrophic growth, the strain oxidized thiosulfate, tetrathionate and elemental sulfur. For growth, the optimum temperature was 42–45 °C and the optimum pH was 6.8–8.2. The cells were Gram-stain-negative, catalase-positive and oxidase-positive. The strain exhibited changes in morphology depending on growth temperature. Cells grown at the optimum temperature were rod-shaped (0.9–3.0 μm long and 0.3–0.5 μm wide), whereas a filamentous form was observed when the strain was cultured at the lowest permissive growth temperatures. The G+C content of genomic DNA was 69 mol%. The major components in the fatty acid profile were C16 : 0, summed feature 3 (C16 : 1ω7c and/or C16 : 1ω6c) and summed feature 9 (iso-C17 : 1ω9c and/or 10-methyl C16 : 0). Phylogenetic analysis based on 16S rRNA gene sequences indicated that the closest cultivated relative of strain skN76T was Acidiferrobacter thiooxydans m-1T, with sequence similarity of 93 %. On the basis of its phylogenetic and phenotypic properties, strain skN76T ( = DSM 100313T = NBRC 110942T) is proposed as the type strain of a novel species of a novel genus, Sulfurifustis variabilis gen. nov., sp. nov. Novel taxa, Acidiferrobacteraceae fam. nov. and Acidiferrobacterales ord. nov., are also proposed to accommodate the genera Acidiferrobacter and Sulfurifustis gen. nov.