Unraveling the mechanism of assimilatory nitrate reduction and methane oxidation by Methylobacter sp. YHQ through dual N-O isotope analysis and kinetic modeling
Chen G. Hao Q. Zeng R.J. Kappler A. Li X. Yue F. Hu S. Yang Y. Liu F. Li H. Qian D. Yang B. Sarkytkan K. Liu T. Li F.
December 2024Springer Nature
Carbon Research
2024#3Issue 1
Assimilatory nitrate reduction and methane (CH4) oxidation by bacteria play important roles in carbon (C) and nitrogen (N) biogeochemical cycles. Here, an investigation of enzymatic assimilatory nitrate reduction and CH4 oxidation by Methylobacter sp. YHQ from the wetlands is presented, specifically concentrating on N and oxygen (O) isotope fractionation with various initial nitrate and oxygen concentrations. The N enrichment factors (15εassimilation) increased from 4.2 ± 0.7‰ to 6.9 ±1.3‰ and the O isotope enrichment factors (18εassimilation) increased from 2.7 ± 0.9‰ to 4.7 ± 0.8‰ during nitrate assimilation when initial nitrate concentrations increased from 0.9 mM to 2 mM. Similar 18ε and 15ε values were observed at different oxygen concentrations. The values of 18ε and 15ε provided vital parameters for the assessment of assimilatory nitrate reduction via the Rayleigh equation approach. The ratios of O and N isotope enrichment factors (18ε:15ε)assimilation ranged from 0.64 ± 0.15 to 0.74 ± 0.18 during nitrate assimilation by Methylobacter sp. YHQ with Nas, which were different from (18ε:15ε)assimilation for assimilatory eukaryotic nitrate reductase (eukNR) from literature data. Thus, N and O isotope fractionation could be useful tools to distinguish eukNR from Nas during nitrate assimilation. Additionally, the rates of CH4 oxidation and nitrate reduction were evaluated with a reaction-based kinetic model, and it quantitatively described the enzymatic reactions of nitrate assimilation. Combining dual N-O isotope analysis with kinetic modeling provides new insights into the microbially driven C-N interactions. Graphical Abstract: (Figure presented.)
Assimilatory nitrate reduction , CH4 oxidation , Freshwater bacteria , N and O isotopes , Nas and eukNR
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National-Regional Joint Engineering Research Center for Soil Pollution Control and Remediation in South China, Guangdong Key Laboratory of Integrated Agro-environmental Pollution Control and Management, Institute of Eco-environmental and Soil Sciences, Guangdong Academy of Sciences, Guangzhou, 510650, China
Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fujian, Fuzhou, 350002, China
Geomicrobiology, Center for Applied Geoscience, University of Tübingen, Tübingen, 72076, Germany
Cluster of Excellence: EXC 2124: Controlling Microbes to Fight Infection, Tübingen, 72074, Germany
SCNU Environmental Research Institute, Guangdong Provincial Key Laboratory of Chemical Pollution and Environmental Safety & amp; MOE Key Laboratory of Theoretical Chemistry of Environment, South China Normal University, Guangzhou, 510006, China
Institute of Surface-Earth System Science, School of Earth System Science, Tianjin University, Tianjin, 300072, China
Xinjiang Key Laboratory of Clean Conversion and High Value Utilization of Biomass Resources, Yili Normal University, Yining, 835000, China
Department of Geography and Ecology, Institute of Natural Sciences and Geography, Abai Kazakh National Pedagogical University, Almaty, Kazakhstan
National-Regional Joint Engineering Research Center for Soil Pollution Control and Remediation in South China
Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation
Geomicrobiology
Cluster of Excellence: EXC 2124: Controlling Microbes to Fight Infection
SCNU Environmental Research Institute
Institute of Surface-Earth System Science
Xinjiang Key Laboratory of Clean Conversion and High Value Utilization of Biomass Resources
Department of Geography and Ecology
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