title: Carbon dioxide concentration dictates alternative methanogenic pathways in oil reservoirs.
abstract: Deep subsurface formations (for example, high-temperature oil reservoirs) are candidate sites for carbon capture and storage technology. However, very little is known about how the subsurface microbial community would respond to an increase in CO2 pressure resulting from carbon capture and storage. Here we construct microcosms mimicking reservoir conditions (55 °C, 5 MPa) using high-temperature oil reservoir samples. Methanogenesis occurs under both high and low CO2 conditions in the microcosms. However, the increase in CO2 pressure accelerates the rate of methanogenesis to more than twice than that under low CO2 conditions. Isotope tracer and molecular analyses show that high CO2 conditions invoke acetoclastic methanogenesis in place of syntrophic acetate oxidation coupled with hydrogenotrophic methanogenesis that typically occurs in this environment (low CO2 conditions). Our results present a possibility of carbon capture and storage for enhanced microbial energy production in deep subsurface environments that can mitigate global warming and energy depletion.
authors.affiliation: Institute for Geo-Resources and Environment, National Institute of Advanced Industrial Science and Technology, 1-1-1 Higashi, Tsukuba 305-8567, Japan.
authors.forename: Daisuke
authors.initials: D
authors.lastname: Mayumi
authors.forename: Jan
authors.initials: J
authors.lastname: Dolfing
authors.forename: Susumu
authors.initials: S
authors.lastname: Sakata
authors.forename: Haruo
authors.initials: H
authors.lastname: Maeda
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Miyagawa
authors.forename: Masayuki
authors.initials: M
authors.lastname: Ikarashi
authors.forename: Hideyuki
authors.initials: H
authors.lastname: Tamaki
authors.forename: Mio
authors.initials: M
authors.lastname: Takeuchi
authors.forename: Cindy H
authors.initials: CH
authors.lastname: Nakatsu
authors.forename: Yoichi
authors.initials: Y
authors.lastname: Kamagata
mesh_terms: D000085:Acetates / Q000378:metabolism; D001105:Archaea / Q000187:drug effects / Q000378:metabolism; D002245:Carbon Dioxide / Q000494:pharmacology*; D002247:Carbon Isotopes; D008697:Methane / Q000096:biosynthesis*; D064307:Microbiota / Q000187:drug effects*; D008969:Molecular Sequence Data; D061329:Oil and Gas Fields / Q000382:microbiology*; D010084:Oxidation-Reduction / Q000187:drug effects; D010313:Partial Pressure; D013816:Thermodynamics
chemical_list: D000085:Acetates; D002247:Carbon Isotopes; D002245:Carbon Dioxide; D008697:Methane