Potential for microbial H and metal transformations associated with novel bacteria and archaea in deep terrestrial subsurface sediments

Hernsdorf, A. W.*; Amano, Yuki; Miyakawa, Kazuya; Ise, Kotaro; Suzuki, Yohei*; Anantharaman, K.*; Probst, A. J.*; Burstein, David*; Thomas, B. C.*; Banfield, J. F.*

ISME Journal, 11, p.1915 - 1929, 2017/03

AA2016-0002.pdf:2.21MB

https://doi.org/10.1038/ismej.2017.39

To evaluate the potential for interactions between microbial communities and disposal systems, we explored the structure and metabolic function of a sediment-hosted subsurface ecosystem associated with Horonobe Underground Research Center, Hokkaido, Japan. Overall, the ecosystem is enriched in organisms from diverse lineages and many are from phyla that lack isolated representatives. The majority of organisms can metabolize H, often via oxidative [NiFe] hydrogenases or electron-bifurcating [FeFe] hydrogenases that enable ferredoxin-based pathways, including the ion motive Rnf complex. Many organisms implicated in H metabolism are also predicted to catalyze carbon, nitrogen, iron, and sulfur transformations. Notably, iron-based metabolism was predicted in a bacterial lineage where this function has not been predicted previously and in an ANME-2d archaeaon that is implicated in methane oxidation. We infer an ecological model that links microorganisms to sediment-derived resources and predict potential impacts of microbial activity on H accumulation and radionuclide migration.

Carbon steel corrosion induced by microbial community in soil environment and its analysis

Hirano, Shinichi*; Nagaoka, Toru*; Ise, Kotaro; Amano, Yuki; Matsumoto, Norio*

Zairyo To Kankyo, 64(12), p.535 - 539, 2015/12

https://doi.org/10.3323/jcorr.64.535

To obtain the knowledge about the corrosion ability and its mechanism as a target the soil environment microorganisms, lake mud was cultured with metallic iron. As a result, corrosion of carbon steel was observed with sulfate reduction and methane producing activity in brackish medium with lactate as substrate. Inhibition test of SRB and MPA suggested that SRB plays a major role for this corrosion, and MPA enhanced corrosion activity by the coexistence of SRB.

Microbial structure change in the groundwater samples from two boreholes at depths of -250m in Horonobe Underground Research Laboratory

Ise, Kotaro; Nanjo, Isao; Amamiya, Hiroki; Amano, Yuki; Iwatsuki, Teruki; Asano, Takahiro*; Kageyama, Koji*; Sasaki, Yoshito; Yoshikawa, Hideki

no journal, , 

no abstracts in English

Development of evaluation code for microbial effect on HLW disposal, 2; Sensitivity analysis of microbial colloid effects on radionuclide transport by COLFRAC

Ise, Kotaro; Ito, Tsuyoshi; Amano, Yuki; Yoshikawa, Hideki

no journal, , 

To evaluate microbial colloid-facilitated radionuclide transport in fractured porous media, we conducted sensitivity analyses using a two dimentional numerical code, COLFRAC-mrl. The targeted domain is 100 0.2 m granitic rock which contain strait fracture in the center. The fracture aperture was set to 1.1810 m and groundwater velocity in the fracture was set to 50 m/y. The results of sensitivity analyses showed that if there are microbe in the order of 10 cells/L in the groundwater, these microbe have possibilities to facilitate radionuclide transport.

Reduction of red iron oxide by iron reducing bacteria cultured from Yoshida Nakamichi site in Tottori City, Tottori Prefecture

Lee, S.*; Taniguchi, Tomoko*; Ise, Kotaro; Yoshikawa, Hideki

no journal, , 

In this study, we investigated the reduction ability of red iron oxide by iron reducing bacteria cultured from Yoshida Nakamichi site in Tottori City, Tottori Prefecture. We report that the results of comparison of morphological characteristic for red iron oxide between commercial product and buried cultural properties.

Spatial distribution of microbial populations and carbon cycle in the subsurface environment of the Horonobe area, Hokkaido, Japan

Amano, Yuki; Ise, Kotaro; Terashima, Motoki; Sasaki, Yoshito; Amamiya, Hiroki; Yoshikawa, Hideki

no journal, , 

Microorganisms are widely distributed in the subsurface environments. However, the distribution, role and rate of metabolisms, and the origin of the activity are not well known. In this study, we investigated deep groundwater samples of sedimentary rocks, which is contained supersuturated methane and carbon dioxide, using boreholes in the Horonobe Underground Research Laboratory (URL), in the northern part of Hokkaido, Japan. Abundant methanogens were detected in the groundwater, and 80% of them were related to Methanoregula boonei and Methanobacterium flexile that can utilize hydrogen and carbon dioxide as methanogenesis. Phylotypes clustered within the phylum Firmicutes, beta-Proteobacteria, delta-Proteobacteria and Candidatte division TM7 were dominant in the groundwater samples. Laboratory experiment using culture a technique showed that humic substances purified from Horonobe area could be degraded by microorganisms. Our results suggest that microbial spatial distribution in the subsurface environment was correlate closely with geochemical conditions, such as redox condition and carbon sources.

An Analogue study for heavy metal adsorption onto biofilm in the deep subsurface environment of the Horonobe area, Hokkaido, Japan

Amano, Yuki; Ise, Kotaro; Ito, Tsuyoshi; Nemoto, Kazuaki; Tachi, Yukio

no journal, , 

We characterized the geochemical and microbial structures of biofilm samples formed with groundwater from boreholes in the subsurface environment at Horonobe area, Japan. The biofilm samples were grown naturally into the sampling tubes made by nylon under in-situ geochemical conditions. The heavy metal sorption capacities of these biofilms were also determined to evaluate the effects of microorganims on radionuclides transport in HLW systems. From the results of heavy metal analyses, it is revealed that high content of elements was accumulated in the biofilms, and each elements was not accumulated in quantity in the same proportion and had different sorption properties. We could find no discernible correlation between those elements accumulated in the biofilms and the composition of groundwaters. It is assumed that these differences depend on the microbial community structure that composed of biofilms. That is to say, it is possible that microorganims that compose the biofilms selectively accumulate heavy metals according to their metabolic activity. Analyses of 16S rDNA utilizing next generation sequencing indicates that the biofilms were dominated by the phylum Nitrospirae, Proteobacteria, and JS1 and SM1 as Candidate phylum. Over 40% of the detected sequences belong to groups of uncultured microorganisms. These results possibly show the similar characteristics of natural biofilms formed on fracture-surfaces in the subsurface environments. Hence, it is necessary to evaluate mechanisms of interaction between heavy metals, microbial community structure and metabolic activities of biofilms.