Page 122 - Microbial methane cycling in a warming world From biosphere to atmosphere Michiel H in t Zandt

Chapter 5. Early Holocene carbon storage and microbial activity in North Sea peats
Archaeal 16S rRNA gene copy numbers ranged from 1.3 to 8.1 x 107, while bacterial 16S rRNA
gene copy numbers ranged from 1.7 to 3.2 x 106.
Dominance of Bathyarchaeia and prevalence of methanogenic archaea
Bathyarchaeia dominated the archaeal communities at all locations, with an average relative abundance of 71% (range 35.9-92.2%). The relative abundance of Bathyarchaeia was highest at the Max Gundelach site, with an average of 86% of the archaeal 16S rRNA gene reads. The phylum Bathyarchaeia is a potentially metabolically diverse microbial group that is found in a wide range of organic-rich environments, including deep sea and freshwater sediments (Evans et al. 2015). Among the four sites for which DNA sequencing was performed, methanogenic archaea were detected at Vittorio, Max Gundelach and Westland but not Senator Westphal S (Fig. 5). Methanogenic archaeal species belonging to Methanomassiliicoccaceae were detected in these three cores, whereas Methanoregulaceae were only observed at Max Gundelach. The Max Gundelach site contained the highest relative abundance of methanogenic archaea, with an average of 10.3%, compared to averages of 3.9% and 3.0% at the Vittorio and Westland sites, respectively.
Lokiarchaea were most abundant at the Vittorio site (32.2%) and were present at only low abundance at the Westland site (2.8%) and below the 2% threshold at the other sites (Fig. 5). Marine Benthic Group D and DHVEG-1 were more abundant at the Senator Westphal S and Westland sites (30.3% and 21.2%, respectively) and were present only at low abundance at the Vittorio and Max Gundelach sites (1.4% and 2.7%, respectively). Genomic analysis of the Asgard candidate phylum “Candidatus Lokiarchaeota” has indicated potential for an acetogenic lifestyle, hydrogen dependency and mixotrophic potential (Sousa et al. 2016; Spang et al. 2019).
Diverse bacterial communities dominated by candidate phylum JS1
Candidate phylum JS1 dominated the bacterial communities, with an average relative abundance of 22.9% (Fig. 5). The highest relative abundances, 33.7% and 26.3%, were observed at the Vittorio and Max Gundelach sites, respectively. Dehalococcoidia were mainly observed at the Vittorio and Max Gundelach sites, with respective abundances of 12.3% and 18.4%. At the Senator Westphal S and Westland sites, the abundances of Dehalococcoidia were
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