title: Activation of CO2-reducing methanogens in oil reservoir after addition of nutrient.
abstract: Nutrient addition as part of microbial enhanced oil recovery (MEOR) operations have important implications for more energy recovery from oil reservoirs, but very little is known about the in situ response of microorganisms after intervention. An analysis of two genes as biomarkers, mcrA encoding the key enzyme in methanogenesis and fthfs encoding the key enzyme in acetogenesis, was conducted during nutrient addition in oil reservoir. Clone library data showed that dominant mcrA sequences changed from acetoclastic (Methanosaetaceae) to CO2-reducing methanogens (Methanomicrobiales and Methanobacteriales), and the authentic acetogens affiliated to Firmicutes decreased after the intervention. Principal coordinates analysis (PCoA) and Jackknife environment clusters revealed evidence on the shift of the microbial community structure among the samples. Quantitative analysis of methanogens via qPCR showed that Methanobacteriales and Methanomicrobiales increased after nutrient addition, while acetoclastic methanogens (Methanosaetaceae) changed slightly. Nutrient treatment activated native CO2-reducing methanogens in oil reservoir. The high frequency of Methanobacteriales and Methanomicrobiales (CO2-reducers) after nutrient addition in this petroleum system suggested that CO2-reducing methanogenesis was involved in methane production. The nutrient addition could promote the methane production. The results will likely improve strategies of utilizing microorganisms in subsurface environments.
authors.affiliation: State Key Laboratory of Bioreactor Engineering and Institute of Applied Chemistry, East China University of Science and Technology, Shanghai 200237, PR China.
authors.forename: Guang-Chao
authors.initials: GC
authors.lastname: Yang
authors.affiliation: State Key Laboratory of Bioreactor Engineering and Institute of Applied Chemistry, East China University of Science and Technology, Shanghai 200237, PR China.
authors.forename: Lei
authors.initials: L
authors.lastname: Zhou
authors.affiliation: State Key Laboratory of Bioreactor Engineering and Institute of Applied Chemistry, East China University of Science and Technology, Shanghai 200237, PR China; Shanghai Collaborative Innovation Center for Biomanufacturing Technology, Shanghai 200237, PR China.
authors.forename: Serge Maurice
authors.initials: SM
authors.lastname: Mbadinga
authors.affiliation: Huabei Oilfield, PetroChina, Renqiu, Hebei 062552, PR China.
authors.forename: Jing
authors.initials: J
authors.lastname: You
authors.affiliation: Huabei Oilfield, PetroChina, Renqiu, Hebei 062552, PR China.
authors.forename: Hua-Zhen
authors.initials: HZ
authors.lastname: Yang
authors.affiliation: State Key Laboratory of Bioreactor Engineering and Institute of Applied Chemistry, East China University of Science and Technology, Shanghai 200237, PR China.
authors.forename: Jin-Feng
authors.initials: JF
authors.lastname: Liu
authors.affiliation: State Key Laboratory of Bioreactor Engineering and Institute of Applied Chemistry, East China University of Science and Technology, Shanghai 200237, PR China.
authors.forename: Shi-Zhong
authors.initials: SZ
authors.lastname: Yang
authors.affiliation: School of Biological Sciences, The University of Hong Kong, Pokfulam Road, Hong Kong SAR, PR China.
authors.forename: Ji-Dong
authors.initials: JD
authors.lastname: Gu
authors.affiliation: State Key Laboratory of Bioreactor Engineering and Institute of Applied Chemistry, East China University of Science and Technology, Shanghai 200237, PR China; Shanghai Collaborative Innovation Center for Biomanufacturing Technology, Shanghai 200237, PR China. Electronic address: bzmu@ecust.edu.cn.
authors.forename: Bo-Zhong
authors.initials: BZ
authors.lastname: Mu
mesh_terms: D002245:Carbon Dioxide / Q000378:metabolism*; D019605:Euryarchaeota / Q000235:genetics / Q000378:metabolism; D008697:Methane / Q000096:biosynthesis*; D017018:Methanomicrobiales / Q000235:genetics / Q000378:metabolism*; D019640:Methanosarcinales / Q000235:genetics / Q000378:metabolism*; D061329:Oil and Gas Fields / Q000737:chemistry / Q000382:microbiology*; D010578:Petroleum / Q000382:microbiology*; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000235:genetics
chemical_list: D010578:Petroleum; D012336:RNA, Ribosomal, 16S; D002245:Carbon Dioxide; D008697:Methane
keywords: Microbial enhanced energy recovery; Oil reservoir; Quantitative real-time PCR; fthfs; mcrA