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Microb Cell Fact. 2016 Jan 14;15:11. doi: 10.1186/s12934-015-0397-z.

Reversing methanogenesis to capture methane for liquid biofuel precursors.

Author information

1
Department of Chemical Engineering, The Pennsylvania State University, University Park, PA, 16802-4400, USA. valwc.soo@gmail.com.
2
Department of Chemical Engineering, The Pennsylvania State University, University Park, PA, 16802-4400, USA. mum278@psu.edu.
3
Department of Chemical Engineering, The Pennsylvania State University, University Park, PA, 16802-4400, USA. sript.art@gmail.com.
4
Department of Chemical Engineering, The Pennsylvania State University, University Park, PA, 16802-4400, USA. zhufy6@hotmail.com.
5
Department of Veterinary and Biomedical Sciences, The Pennsylvania State University, University Park, PA, 16802-4400, USA. luz26@psu.edu.
6
Key Laboratory of Magnetic Resonance in Biological Systems, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan, 430071, China. luz26@psu.edu.
7
Department of Chemistry, The Pennsylvania State University, University Park, PA, 16802-4400, USA. euc15@psu.edu.
8
The Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, PA, 16802-4400, USA. pbs13@psu.edu.
9
Institute of Natural and Mathematical Sciences, Massey University, Auckland, 0632, New Zealand. saumya.agrawal@gmail.com.
10
Department of Chemical Engineering, The Pennsylvania State University, University Park, PA, 16802-4400, USA. hnbokaee@psu.edu.
11
Department of Chemical Engineering, The Pennsylvania State University, University Park, PA, 16802-4400, USA. sxg375@psu.edu.
12
Department of Chemical Engineering, The Pennsylvania State University, University Park, PA, 16802-4400, USA. salis@psu.edu.
13
Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA, 16802-4400, USA. jgf3@psu.edu.
14
Department of Chemical Engineering, The Pennsylvania State University, University Park, PA, 16802-4400, USA. costas@engr.psu.edu.
15
Department of Veterinary and Biomedical Sciences, The Pennsylvania State University, University Park, PA, 16802-4400, USA. adp117@psu.edu.
16
Department of Chemical Engineering, The Pennsylvania State University, University Park, PA, 16802-4400, USA. tuw14@psu.edu.
17
Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA, 16802-4400, USA. tuw14@psu.edu.

Abstract

BACKGROUND:

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.

RESULTS:

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 FeCl3 as an electron acceptor. Accordingly, increases in cell density and total protein were observed as cells grew on methane in a biofilm on solid FeCl3. When incubated on methane for 5 days, high-densities of ANME-1 Mcr-producing M. acetivorans cells consumed 15 ± 2 % methane (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 (13)C isotopic labeling of methane and bicarbonate coupled with nuclear magnetic resonance and gas chromatography/mass spectroscopy, as well as RNA sequencing.

CONCLUSIONS:

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.

PMID:
26767617
PMCID:
PMC4714516
DOI:
10.1186/s12934-015-0397-z
[Indexed for MEDLINE]
Free PMC Article

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