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Saito, Yoshimoto*; Hirano, Shinichi*; Nagaoka, Toru*; Amano, Yuki
Ecological Genetics and Genomics, 12, p.100042_1 - 100042_9, 2019/10
Culture-independent molecular techniques enable us to analyze microflora in various environments. Many uncultured prokaryotes have been detected by the molecular methods from extreme environments, including anaerobic, no light, high-pressure, and high temperature. Recently, microbial eukaryotes were also detected in deep-sea environments, suggesting that microbial eukaryotes can adapt to a wider range of environments than previously thought. Here, we performed a culture-independent analysis of eukaryotes from approximately -250 m depth in the Horonobe Underground Research Laboratory at Horonobe, Japan. Our results indicate that fungi are the dominant eukaryotic flora in deep sedimentary rocks of Horonobe. We detected a wide range of species, including Zygomycete, Basidiomycete, and Ascomycete fungi from the rocks. This study is the first report of eukaryotic diversity in deep subsurface sedimentary rocks.
Hirano, Shinichi*; Nagaoka, Toru*; Ise, Kotaro; Amano, Yuki; Matsumoto, Norio*
Zairyo To Kankyo, 64(12), p.535 - 539, 2015/12
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.
Yoshikawa, Hideki; Ito, Tsuyoshi; Sasaki, Yoshito; Asano, Takahiro*; Nagaoka, Toru*; Nakamura, Takamichi*
no journal, ,
This report shows that PHREEQC-2 code are used to analyzed a laboratory experimental for water-microbe interaction using a microbe collected from groundwater of Horonobe area, in order to evaluate influence by the microbe activity on the chemical composition of the water to contribute to the performance assessment of the disposal of the high-level radioactive waste. As a results, we understood that behavior such as the oxygen consumption could be estimated with the microbe influence.
Nagaoka, Toru*; Nakamura, Takamichi*; Sasaki, Yoshito; Asano, Takahiro*; Ito, Tsuyoshi*; Amano, Yuki; Iwatsuki, Teruki; Yoshikawa, Hideki
no journal, ,
Laboratory jar experiment was conducted with deep subsurface sedimentary rock and groundwater, in order to assess the response of the geochemical and microbial communities toward redox processes. The redox process was induced by exposure to air and discontinuation to sediment suspension, which simulated the process occurring during operation of nuclear waste repositories. As a results, after discontinuation of air exposure with lactate amendment, redox potentials decreased from ca. +100 mV to -600 m V (vs. Ag/AgCl), and some sequential terminal electron-accepting process (TEAPs) was observed with the reactions of aerobic respiration, iron reduction and hygrogen fermentation. The related species of the microbes along with TEAPs, e.g., Pseudomonas sp. for aerobic respiration and Shewanella sp. for iron reduction, was also detected. These results indicated that the microbial activities would affect the geochemical changes in nuclear repositories.
Amano, Yuki; Nanjo, Isao; Iwatsuki, Teruki; Sasaki, Yoshito; Asano, Takahiro; Terashima, Motoki; Nagaoka, Toru*; Nakamura, Takamichi*; Yoshikawa, Hideki; Aoki, Kazuhiro
no journal, ,
In-situ experiment of redox reaction was conducted to assess the redox buffur capacity of water-rock-microbes system in the subsurface environment at 140 m depth of Horonobe Underground Research Laboratory. Dissolved oxygen was injected into a borehole, and the physico-chemical parameters (i.e. pH, ORP, DO, EC, etc.) and geochemical composition, microbial cell number, and microbial community structure were monitored continuously during the groundwater circulation. DO concentration could not detected after 10 hours from the injection. The concentration of Fe(II) was decreased with time, then the injected oxygen could be consumed by Fe(II). The rate of oxygen consumption during the experiment was 9.64 mg/L/day. The Eh value become stable at -208 mV after 5 days, then it showed that the reducing condition would be recovered quickly after closed condition.
Amano, Yuki; Iwatsuki, Teruki; Nanjo, Isao; Sasaki, Yoshito; Asano, Takahiro*; Yoshikawa, Hideki; Nagaoka, Toru*; Nakamura, Takamichi*
no journal, ,
In situ experiments for assessment of redox buffer capacity were conducted at 140 m depth of Horonobe Under Research Laboratory, and demonstrated to recover reducing condition from the oxidation condition by "water-rock-microbes" interactions.
Amano, Yuki; Beppu, Hikari*; Ono, Hirokazu; Taniguchi, Naoki; Hirano, Shinichi*; Matsumoto, Norio*; Nagaoka, Toru*
no journal, ,
Hirano, Shinichi*; Nagaoka, Toru*; Matsumoto, Norio*; Amano, Yuki
no journal, ,
In this presentation, we will introduce case studies of microbial effects on engineering barrier systems in geological disposal systems. The results of the metal corrosion experiments using mixtures of Kunigel V1 and sand as a buffer material and anaerobic metal reducing microbial consortium will be presented in this talk.
Nagaoka, Toru*; Hirano, Shinichi*; Matsumoto, Norio*; Amano, Yuki
no journal, ,
no abstracts in English
Nagaoka, Toru*; Hirano, Shinichi*; Matsumoto, Norio*; Amano, Yuki
no journal, ,
Nagaoka, Toru*
no journal, ,
Spent nuclear fuel (SF) and other high-level radioactive wastes (HLW) from nuclear energy production must be stored safely for at least 100,000 years. The safety requirements for HLW and SF disposal call for metallic containers to remain intact for a long period of time. Microbial activity in bentonite buffer materials in deep geological repository is of concern for microbiologically influenced corrosion which could affect the longevity of metallic containers. In this lecture, laboratory examinations of microbial abundance and activities in compacted bentonite buffer materials will be introduced.
Nagaoka, Toru*; Hirano, Shinichi*; Matsumoto, Norio*; Amano, Yuki
no journal, ,
Sena, C.*; Molinero, J.*; Nagaoka, Toru*; Ajima, Shuji*; Ito, Tsuyoshi; Sasaki, Yoshito; Asano, Takahiro; Yoshikawa, Hideki
no journal, ,
Hirano, Shinichi*; Nagaoka, Toru*; Matsumoto, Norio*; Amano, Yuki
no journal, ,
no abstracts in English
Nagaoka, Toru*; Hirano, Shinichi*; Matsumoto, Norio*; Amano, Yuki; Ise, Kotaro; Yoshikawa, Hideki
no journal, ,
no abstracts in English
