JpGU-AGU Joint Meeting 2017

Presentation information

[JJ] Oral

M (Multidisciplinary and Interdisciplinary) » M-IS Intersection

[M-IS19] [JJ] Biogeochemistry

Wed. May 24, 2017 10:45 AM - 12:15 PM 302 (International Conference Hall 3F)

convener:Muneoki Yoh(Tokyo University of Agriculture and Technology), Hideaki Shibata(Field Science Center fot Northern Biosphere, Hokkaido University), Naohiko Ohkouchi(Japan Agency for Marine-Earth Science and Technology), Youhei Yamashita(Faculty of Environmental Earth Science, Hokkaido University), Chairperson:Keisuke Koba(Center for Ecological Research, Kyoto University), Chairperson:Michinari Sunamura(University of Tokyo Dept. of Earth & Planetary Science), Chairperson:Rota Wagai(NARO, Institute for Agro-Environmental Sciences), Chairperson:Kazuya Nishina(National Institute for Enviromental Studies)

10:45 AM - 11:00 AM

[MIS19-07] Structure and functions of a methane-driven microbial food chain in rice field soil

*Jun Murase1, Yuko Hibino1, Takeshi Tokida2, Takashi Okubo2, Miwa Arai2, Kentaro Hayashi2, Hidemitsu Sakai2, Toshihiro Hasegawa2 (1.Graduate School of Bioagricultural Sciences, Nagoya University, 2.Institute for Agro-Environmental Sciences, NARO)

Keywords:Paddy soil, Protists, Protozoa, Methane oxidaiton, Foodweb

Methane oxidation is a key process controlling methane emission from wetlands into the atmosphere. Methanotrophs, responsible for aerobic methane oxidation, do not only oxidize but also assimilate methane. Once assimilated, methane carbon may be utilized by other organisms. Here we present the evidence of a methane-driven microbial food chain in a rice field soil and its potential impact on methanotrophs. Stable-isotope probing of nucleic acids using 13C-labelled methane demonstrated that methane carbon is incorporated not only into methanotrophs but also into non-methanotrophic bacteria, phagotrophic protists, bacteriovorus nematodes in a rice field soil. Methane carbon could be also incorporated into the capsid gene of T4 type bacteriophages. These results suggest that methane carbon is linked to the soil microbial food chain that involves cross feeding, grazing, and viral lysis—once assimilated. The rice rhizosphere—the active site of methane oxidation—can have a distinct community of phagotrophic protists involved in a methanotrophic food chain that is influenced by elevated atmospheric CO2; this implies a variation of prey-predator interaction in the methanotrophic food chain. Protistan grazing shapes the community structure of methanotrophs most likely by selective grazing. Protistan grazing also has a potential to affect methane oxidation in the surface of water-saturated rice field soil. Altogether, a series of our study suggests the potential importance of microbe-microbe interactions in methane dynamics in a rice field soil.