Genetic survey of indigenous microbial eukaryotic communities, mainly fungi, in sedimentary rock matrices of deep terrestrial subsurface

Saito, Yoshimoto*; Hirano, Shinichi*; Nagaoka, Toru*; Amano, Yuki

Ecological Genetics and Genomics, 12, p.100042_1 - 100042_9, 2019/10

https://doi.org/10.1016/j.egg.2019.100042

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.

Annual report on the effluent control of low level liquid waste in Nuclear Fuel Cycle Engineering Laboratories FY2016

Nakano, Masanao; Fujita, Hiroki; Nagaoka, Mika; Inoue, Kazumi; Koike, Yuko; Yoshii, Hideki*; Hiyama, Yoshinori*; Otani, Kazunori*; Kikuchi, Masaaki*; Sakauchi, Nobuyuki*; et al.

JAEA-Review 2017-037, 119 Pages, 2018/03

JAEA-Review-2017-037.pdf:2.58MB

Based on the regulations (the safety regulation of Tokai Reprocessing Plant, the safety regulation of nuclear fuel material usage facilities, the radiation safety rule, the regulation about prevention from radiation hazards due to radioisotopes, which are related with the nuclear regulatory acts, the local agreement concerning with safety and environment conservation around nuclear facilities, the water pollution control law, and bylaw of Ibaraki Prefecture), the effluent control of liquid waste discharged from the Nuclear Fuel Cycle Engineering Laboratories of Japan Atomic Energy Agency has been performed. This report describes the effluent control results of the liquid waste in the fiscal year 2016. In this period, the concentrations and the quantities of the radioactivity in liquid waste discharged from the reprocessing plant, the plutonium fuel fabrication facilities, and the other nuclear fuel material usage facilities were much lower than the limits authorized by the above regulations.

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.

In situ experiment for redox buffer capacity in the subsurface environment

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.

Simulation of microbially mediated redox changes with Horonobe sedimentary rock and groundwater, 3; Analysis using PHREEQC code

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.

Microbially mediated redox processes in lactate stimulation with sedimentary rock and groundwater

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.

Analysis of microbial influenced corrosion in compacted buffer materials

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.

Microbial influenced corrosion of carbon steel in compacted buffer material composed of Kunigel V1 and sand mixture

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

no journal, , 

Corrosion of carbon steel in compacted bentonite buffer materials using anaerobic corrosive microbial consortium

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

no journal, , 

Laboratory examinations of microbial abundance and activity in compacted bentonite buffer materials

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.