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“Methanogenesis 2020 – An update”
EGU General Assembly 2020 Online | 7 May 2020
Frank Keppler
Institute of Earth Sciences Heidelberg University
Germany
Methanogenesis – traditional view
biotic abiotic
biomass burning
serpentinisation
rice paddies, mires, lakes, wetlands, landfills …
archaea
geological
anoxic
decay of organic matter
guts of ruminants
or termites
biomass burning fossil sources
energy production
Fischer-Tropsch-process
industry
microbial
CO2 + 4H2 CH4 + 2H2O
CH3COOH CH4 + CO2
Well known processes of methane formation on Earth
ocean floor
Prokaryotes Archaea
The final step of methanogenesis by archaea
Me-S-CoM + CoB-SH → CH4 + CoB-S-S-CoM
Ellermann et al., Eur. J. Biochem, 1988
The enzyme Methyl-coenzyme M reductase (MCR) catalyzes the final step in CH4 formation…a phylogenetic marker
Novel eukaryotic sources recently discovered…
as described e.g. by Abdulmajeed &, Qaderi 2017, 2019, 2020, Althoff et al. 2014; Boros & Keppler, 2019; Bruhn et al. 2012; Carmichael et al. 2014; Hartmann et al. 2020, Keppler et al. 2006, 2009; Klintzsch et al. 2019; Lenhart et al. 2012, 2015, 2016; Liu et al. 2015; Wang et al. 2013, 2016,…
Phylogenetic Tree of Life Three domain system
?
[Phylogenetic Tree of Life taken from Wikimedia Commons]
Widespread formation of methane by Cyanobacteria in aquatic and terrestrial environments
Bižić et al., Science Advances, 2020
Thomas Klintzsch, Heidelberg University
Thomas Klintzsch, Heidelberg University
Reported formation rates - from culture experiments:
7
Bižić et al., Science Advances, 2020
Methanogenesis 2020
8 [Phylogenetic Tree of Life taken from Wikimedia Commons]
biomass burning
serpentinisation
decay of organic matter
From https://contemplativepathways.files.wordpress.com/2012/08/cornwalls_glendurgan_lowres.jpg?w=640&h=480
Detailed pathways of non-archaeal methane formation have yet to be discovered…