Page 248 - Microbial methane cycling in a warming world From biosphere to atmosphere Michiel H in t Zandt

Chapter 11. Integration and outlook
microorganisms. The study described in Chapter 10 provides a proof of principle for studying the interaction between methanogens and aerobic methanotrophs under oxygen-limited conditions. Indeed, we observed interactions between methanogens and aerobic methanotrophs that affected the CH4 cycling of the system. This has possible implications for the true methane filtering potential. Therefore, the CH4 filtering capacity could increase due to an attached CH4 sink, which has the potential to reduce ebullitive CH4 emissions.
Both the top-down “ecosystem to organism” as well as the bottom-up “organism to ecosystem” approaches are crucial to unravel the role of microorganisms in an ecosystem (Fig. 2). For the latter, the hunt for novel microorganisms led to various exciting discoveries, including for example the discovery of the Asgardarchaeota superphylum on the Prokaryote- Eukaryote interface (Zaremba-Niedzwiedzka et al. 2017; Imachi et al. 2020). Upon their discovery, several research initiatives were started to unravel their potential role in nature (Macleod et al. 2019; Seitz et al. 2019; Cai et al. 2020). This is just one example of a novel discovery within the archaeal domain, which expanded our understanding of their potential role in a wide diversity of ecosystems in which they were detected. For carbon cycle research, the discovery and description of Bathyarchaeota (omnipresent in organic-rich sediments), which are now linked to organic matter degradation, has led to several exciting findings (He et al. 2016; Wilkins et al. 2018; Yu et al. 2018). Genome-centric approaches could aid in more targeted enrichment and characterization strategies, since most of these microbial groups are so far impossible to obtain in pure cultures and very difficult to enrich. In addition, live-cell fluorescence-activated cell sorting (FACS) techniques can provide a promising tool for rapid enrichment and, potentially, the isolation of pure cultures. It is highly likely that these organisms live in syntrophic consortia and are, therefore, auxotrophic for several essential nutrients and proteins. High-quality genomic data is, therefore, essential to develop proper enrichment strategies.
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