Koji Mori

A novel lineage of sulfate-reducing microorganisms: Thermodesulfobiaceae fam. nov., Thermodesulfobium narugense, gen. nov., sp. nov., a new thermophilic isolate from a hot spring

A novel type of a sulfate-reducing microorganism, represented by strain Na82T, was isolated from a hot spring in Narugo, Japan. The isolate was a moderate thermophilic autotroph that was able to grow on H2/CO2 by sulfate respiration. The isolate could grow with nitrate in place of sulfate, and possessed menaquinone-7 and menaquinone-7(H2) as respiratory quinones. Phylogenetic analysis of the 16S rRNA gene sequence indicated that strain Na82T was a member of the domain Bacteria and distant from any known bacteria, as well as from other sulfate-reducing bacteria (sequence similarities less than 80%). The phylogenetic analysis of the dsrAB gene (alpha and beta subunits of dissimilatory sulfite reductase) sequence also suggested that strain Na82T was not closely related to other sulfate reducers. On the basis of the phenotypic and phylogenetic data, a new taxon is established for the isolate. We proposed the name Thermodesulfobium narugense gen. nov., sp. nov. with strain Na82T (=DSM 14796T=JCM 11510T) as the type strain. Furthermore, a new family, Thermodesulfobiaceae fam. nov., is proposed for the genus.

Methanocalculus pumilus sp. nov., a heavy-metal-tolerant methanogen isolated from a waste-disposal site

A mesophilic hydrogenotrophic methanogen, strain MHT-1T, was isolated from the leachate of a sea-based site for solid waste disposal (the port of Osaka, Japan). Strain MHT-1T was found to be an irregular coccus and was able to use H2/CO2 and formate as energy sources. Acetate was required for growth. The optimum temperature and pH for growth were 35 degrees C and 6.5-7.5, respectively. Strain MHT-1T was resistant to high concentrations of several heavy metals such as CdCl2 and CuSO4. The G+C content of the DNA was 51.9 mol%. Analysis of the 16S rRNA gene revealed that the isolate was a member of the genus Methanocalculus but distinct from its nearest neighbour, Methanocalculus halotolerans, there being a sequence similarity of 98.9%. DNA-DNA hybridization analysis revealed 51% relatedness with the DNA of M. halotolerans strain SEBR 4845T. The optimum NaCl concentration was 1.0%, whereas the optimum in M. halotolerans was 5.0%. A new species, Methanocalculus pumilus, is proposed for strain MHT-1T. The type strain is MHT-1T (= DSM 12632T = JCM 10627T).

Thioprofundum hispidum sp. nov., an obligately chemolithoautotrophic sulfur-oxidizing gammaproteobacterium isolated from the hydrothermal field on Suiyo Seamount, and proposal of Thioalkalispiraceae fam. nov. in the order Chromatiales

A novel mesophilic, facultatively anaerobic, sulfur-oxidizing bacterial strain, designated gps61(T), was isolated from a surface rock sample collected from the hydrothermal field of Suiyo Seamount on the Izu-Bonin Arc in the Western Pacific Ocean. Cells of the isolate were rod-shaped with a single sheathed polar flagellum. Neither extensive internal membranes nor storage materials were present in the cells. In a 20u200a% CO(2) atmosphere, strain gps61(T) grew using thiosulfate, sulfur or tetrathionate as electron donors and oxygen or nitrate as electron acceptors. Other substrates, including organic acids and sugars, did not support growth, indicating that strain gps61(T) was an obligate chemolithoautotroph. 16S rRNA gene sequence analysis revealed that strain gps61(T) was closely related to Thioprofundum lithotrophicum 106(T) (98.5u200a% sequence similarity) in the order Chromatiales. Phylogenetic trees grouped strain gps61(T) and Thioprofundum lithotrophicum in the same cluster along with Thioalkalispira microaerophila and Thiohalophilus thiocyanoxidans, but it was apparent from the analysis that the novel strain had definitely departed from the family lineage. On the basis of its phylogenetic position along with its morphological and physiological characteristics, strain gps61(T) (u200a=u200aNBRC 101261(T) u200a=u200aDSM 18546(T)) represents a novel species of the genus Thioprofundum, for which the name Thioprofundum hispidum sp. nov. is proposed. In addition, we propose a novel family name, Thioalkalispiraceae, in the order Chromatiales, to accommodate the genera Thioalkalispira, Thiohalophilus and Thioprofundum.

Archaeoglobus infectus sp. nov., a novel thermophilic, chemolithoheterotrophic archaeon isolated from a deep-sea rock collected at Suiyo Seamount, Izu-Bonin Arc, western Pacific Ocean

A novel thermophilic, strictly anaerobic archaeon, designated strain Arc51T, was isolated from a rock sample collected from a deep-sea hydrothermal field in Suiyo Seamount, Izu-Bonin Arc, western Pacific Ocean. Cells of the isolate were irregular cocci with single flagella and exhibited blue-green fluorescence at 436 nm. The optimum temperature, pH and NaCl concentration for growth were 70 degrees C, pH 6.5 and 3 % (w/v), respectively. Strain Arc51T could grow on thiosulfate or sulfite as an electron acceptor in the presence of hydrogen. This strain required acetate as a carbon source for its growth, suggesting that the reductive acetyl CoA pathway for CO2 fixation was incomplete. In addition, coenzyme M (2-mercaptoethanesulfonic acid), which is a known methyl carrier in methanogenesis, was also a requirement for growth of the strain. Analysis of the 16S rRNA gene sequence revealed that the isolate was similar to members of the genus Archaeoglobus, with sequence similarities of 93.6-97.2 %; the closest relative was Archaeoglobus veneficus. Phylogenetic analyses of the dsrAB and apsA genes, encoding the alpha and beta subunits of dissimilatory sulfite reductase and the alpha subunit of adenosine-5-phosphosulfate reductase, respectively, produced results similar to those inferred from comparisons based on the 16S rRNA gene sequence. On the basis of phenotypic and phylogenetic data, strain Arc51T represents a novel species of the genus Archaeoglobus, for which the name Archaeoglobus infectus sp. nov. is proposed. The type strain is Arc51T (=NBRC 100649T=DSM 18877T).

Description of Mariniphaga anaerophila gen. nov., sp. nov., a facultatively aerobic marine bacterium isolated from tidal flat sediment, reclassification of the Draconibacteriaceae as a later heterotypic synonym of the Prolixibacteraceae and description of the family Marinifilaceae fam. nov.

A mesophilic, chemoheterotrophic bacterium, strain Fu11-5(T), was isolated from tidal-flat sediment from Tokyo Bay, Chiba, Japan. Cells of strain Fu11-5(T) were facultatively aerobic, Gram-negative, non-sporulating, non-motile and rod-shaped (1.9-6.9 µm long). Strain Fu11-5(T) grew optimally at 35-37 °C and pH 6.5-7.0 and with 1-2% (w/v) NaCl. Oxygen and l-cysteine were used as an alternative electron acceptor and donor, respectively. Strain Fu11-5(T) also grew fermentatively on some pentoses, hexoses and disaccharides and soluble starch. Succinic acid was the major end product from d-glucose. Phylogenetic analysis based on the 16S rRNA gene sequence revealed that strain Fu11-5(T) was affiliated with the order Bacteroidales, and its nearest neighbours were members of the genera Meniscus, Prolixibacter, Sunxiuqinia, Mangrovibacterium and Draconibacterium, with 87-91% sequence similarity. Cell morphology, optimum growth temperature and utilization of sugars of strain Fu11-5(T) distinguished the strain from phylogenetically related bacteria. On the basis of its phenotypic features and phylogenetic position, a novel genus and species are proposed to accommodate strain Fu11-5(T), with the name Mariniphaga anaerophila gen. nov., sp. nov. The type strain of Mariniphaga anaerophila is strain Fu11-5(T) (u200a=JCM 18693(T)u200a=NBRC 109408(T)u200a=DSM 26910(T)). We also propose to combine the family Draconibacteriaceae into the family Prolixibacteraceae as a later heterotypic synonym and to place the distinct sublineage of the genus Marinifilum in the family Marinifilaceae fam. nov.

Thermanaeromonas toyohensis gen. nov., sp. nov., a novel thermophilic anaerobe isolated from a subterranean vein in the Toyoha Mines

A novel thermophilic, strictly anaerobic, thiosulfate-reducing bacterium, designated strain ToBE(T), was isolated from a geothermal aquifer at a depth of 550 m in the Toyoha Mines (Hokkaido, Japan). The cells of this bacterium were rod-shaped (0.6 x 2.6 microm), non-motile and sporulating. Strain ToBE(T) was able to grow on formate, lactate, pyruvate or various sugars in the presence of thiosulfate as an electron acceptor. The strain could grow at 55-73 degrees C and pH 5.5-8.5. The optimum temperature and pH for the growth were 70 degrees C and pH 6.5. The G+C content of the DNA was 49.6 mol %. The major quinone and cellular fatty acids were respectively menaquinone-7 and iso-C15:0 and iso-C17:0. Analysis of the 16S rDNA revealed that the isolate was a member of the gram-positive bacteria and was related to the genus Thermoanaerobacter. However, the phylogenetic tree showed that the strain was distant from any other known bacteria, with sequence similarities of less than 90%. On the basis of phenotypic features and phylogenetic analysis, the name Thermanaeromonas toyohensis gen. nov., sp. nov., is proposed for the isolate, with strain ToBE(T) (= DSM 14490T = JCM 11376T) as the type strain.

An extracellular [NiFe] hydrogenase mediating iron corrosion is encoded in a genetically unstable genomic island in Methanococcus maripaludis

Certain methanogens deteriorate steel surfaces through a process called microbiologically influenced corrosion (MIC). However, the mechanisms of MIC, whereby methanogens oxidize zerovalent iron (Fe0), are largely unknown. In this study, Fe0-corroding Methanococcus maripaludis strain OS7 and its derivative (strain OS7mut1) defective in Fe0-corroding activity were isolated. Genomic analysis of these strains demonstrated that the strain OS7mut1 contained a 12-kb chromosomal deletion. The deleted region, termed “MIC island”, encoded the genes for the large and small subunits of a [NiFe] hydrogenase, the TatA/TatC genes necessary for the secretion of the [NiFe] hydrogenase, and a gene for the hydrogenase maturation protease. Thus, the [NiFe] hydrogenase may be secreted outside the cytoplasmic membrane, where the [NiFe] hydrogenase can make direct contact with Fe0, and oxidize it, generating hydrogen gas: Fe0u2009+u20092u2009H+u2009→u2009Fe2+u2009+u2009H2. Comparative analysis of extracellular and intracellular proteomes of strain OS7 supported this hypothesis. The identification of the MIC genes enables the development of molecular tools to monitor epidemiology, and to perform surveillance and risk assessment of MIC-inducing M. maripaludis.

Gas Transport Properties of Pumice Tuff for Performance Assessment of LLW Disposal Facility

In Japan, some of the radioactive waste with a relatively higher radioactivity concentration from nuclear facilities is to be packaged in rectangle steel containers and disposed of in sub-surface disposal facilities, where normal human intrusion is unlikely to occur. If dissolved oxygen in pore water is consumed by steel corrosion after the closure of the facility, hydrogen gas will be generated from the metallic waste, steel containers and concrete reinforcing bars largely by anaerobic corrosion. If the generated gas accumulates and the gas pressure increases excessively in the facility, the facility’s barrier performance might be degraded by mechanical influences such as fracturing of surrounding rock and cementitious materials or plastic deformation of the bentonite buffer. In this study laboratory experiments for gas and water transport properties of the rock were performed to evaluate gas flow through the rock mass (pumice tuff) around a facility for low level waste disposal. Based on the experimental results two-phase flow properties were evaluated by means of an inverse analysis method. The pumice tuff was subjected to hydraulic conductivity tests, water retention (moisture characteristic) tests, and gas injection tests. Non-linear properties such as relative permeability and water retention curve and hydraulic conductivity as a function of confined stress obtained from these tests are discussed. It was possible to estimate the intrinsic permeability, the relative permeability for gas and water and the water retention curve by applying an inverse analysis method using the multi-phase flow analysis code GETFLOWS and universal sensitivity analysis code UCODE_2005 to the gas injection tests. It was found from this study that gas flow in the pumice tuff is reasonably well described by classical two-phase flow concepts and that the two-phase flow properties can be applied to performance assessment of the facility with regard to the influence of gas generation and migration.Copyright