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Title: Reversing methanogenesis to capture methane for liquid biofuel precursors

Energy from remote methane reserves is transformative; however, unintended release of this potent greenhouse gas makes it imperative to convert methane efficiently into more readily transported biofuels. No pure microbial culture that grows on methane anaerobically has been isolated, despite that methane capture through anaerobic processes is more efficient than aerobic ones. Here we engineered the archaeal methanogen Methanosarcina acetivorans to grow anaerobically on methane as a pure culture and to convert methane into the biofuel precursor acetate. To capture methane, we cloned the enzyme methyl-coenzyme M reductase (Mcr) from an unculturable organism, anaerobic methanotrophic archaeal population 1 (ANME-1) from a Black Sea mat, into M. acetivorans to effectively run methanogenesis in reverse. Starting with low-density inocula, M. acetivorans cells producing ANME-1 Mcr consumed up to 9 ± 1 % of methane (corresponding to 109 ± 12 µmol of methane) after 6 weeks of anaerobic growth on methane and utilized 10 mM FeCl 3 as an electron acceptor. Accordingly, increases in cell density and total protein were observed as cells grew on methane in a biofilm on solid FeCl 3. When incubated on methane for 5 days, high-densities of ANME-1 Mcr-producing M. acetivorans cells consumed 15 ± 2 % methanemore » (corresponding to 143 ± 16 µmol of methane), and produced 10.3 ± 0.8 mM acetate (corresponding to 52 ± 4 µmol of acetate). We further confirmed the growth on methane and acetate production using 13C isotopic labeling of methane and bicarbonate coupled with nuclear magnetic resonance and gas chromatography/mass spectroscopy, as well as RNA sequencing. Lastly, we anticipate that our metabolically-engineered strain will provide insights into how methane is cycled in the environment by Archaea as well as will possibly be utilized to convert remote sources of methane into more easily transported biofuels via acetate.« less
Authors:
 [1] ;  [1] ;  [1] ;  [1] ;  [2] ;  [1] ;  [1] ;  [3] ;  [1] ;  [1] ;  [1] ;  [1] ;  [1] ;  [1] ; ORCiD logo [1]
  1. The Pennsylvania State Univ., University Park, PA (United States)
  2. The Pennsylvania State Univ., University Park, PA (United States); Chinese Academy of Sciences, Wuhan (China)
  3. Massey Univ., Auckland (New Zealand)
Publication Date:
Type:
Accepted Manuscript
Journal Name:
Microbial Cell Factories
Additional Journal Information:
Journal Volume: 15; Journal Issue: 1; Journal ID: ISSN 1475-2859
Publisher:
BioMed Central
Research Org:
National Energy Technology Lab. (NETL), Pittsburgh, PA, and Morgantown, WV (United States)
Sponsoring Org:
USDOE Advanced Research Projects Agency - Energy (ARPA-E)
Country of Publication:
United States
Language:
English
Subject:
09 BIOMASS FUELS; Reverse methanogenesis; Anaerobic oxidation of methane; Methyl-coenzyme M reductase
OSTI Identifier:
1375814