Page 37 - Microbial methane cycling in a warming world From biosphere to atmosphere Michiel H in t Zandt

responsible for about 75% of CH4 emissions. Methanotrophs are the sole biological methane sink and can remove up to 98% of the produced CH4. Recent advances in the field highlight that there still is a terra incognita of CH4 cycling microorganisms that play key roles in the global carbon cycle.
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Chapter 3 focuses on microbial corrosion-protective biofilms that were found on metal sheet piles in carbon-rich peat sediments at the Gouderak pumping station in Zuid-Holland, the Netherlands. We were able to reconstruct the microbial food web of natural protective layers on sheet piles, which showed a high enrichment in methanogenic archaea.
The study described in Chapter 4 aimed at improving biogenic CH4 production from coal well basins. We showed that combined nutrient and acetate amendment induces the growth of a methanogenic community, but that methanogenesis from coal was not stimulated. The amendment strategy is therefore not a sustainable way to transform non-producing coal wells into bioenergy factories.
Chapter 5 describes the geochemistry, microbial diversity, and CH4 cycling potential of Holocene buried peat layers in the North Sea. By using 16S rRNA gene amplicon sequencing and batch activity assays, we found that these layers still contain methanogenic communities that can be rapidly reactivated upon substrate amendment. This has potential implications for their role in the global CH4 cycle.
Chapter 6 reviews the current knowledge on thermokarst lakes and highlights the current knowledge gaps. Thermokarst lakes form as a result of permafrost thaw in predominantly ice- rich Yedoma deposits and are therefore an ecosystem that is rapidly expanding with the onset of climate change. Future climate change will have disproportionate effects on the Arctic, which implies potentially strong consequences for future greenhouse gas fluxes and thaw progression.
Chapter 7 describes the study on the effect of temperature increases and nutrient availability on the CH4 cycling microorganisms in sediments of Alaskan thermokarst lakes. By using batch activity assays and 16S rRNA gene amplicon sequencing, we studied the response of the
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