Page 162 - Microbial methane cycling in a warming world From biosphere to atmosphere Michiel H in t Zandt

Chapter 7. Methane cycling in Arctic thermokarst lake sediments Archaea
Taxonomy Archaea Methanosaetaceae Bathyarchaeota
Rice Cluster II Methanoregulaceae Terrestrial Misc Gp Methanobacteriaceae GOM Arc I
Group C3 pMC2A209 Woesearchaeota Others
Taxonomy Bacteria Spingobacteriia
Gammaproteobacteria Betaproteobacteria Deltaproteobacteria Bacteroidetes VadinHA17 Anaerolineae Epsilonproteobacteria Aminicenantes Bacteroidia
Solibacteres Alphaproteobacteria KD4.96 Ignavibacteria Dehalococcoidia OPB35 Soil Group Others
1.25 x 107 1 x 107 7.5 x 106 5 x 106 2.5 x 106
Emaiksoun Lake
1.75 x 108 1.5 x 108 1.25 x 108 1 x 108 7.5 x 107 5 x 107 2.5 x 107
Emaiksoun Lake
Unamed Lake Bacteria
160
Unamed Lake
Figure 1. Distribution of 16S rRNA gene reads of major archaeal (left) and bacterial phyla (right) in the seven thermokarst lake sediment cores. Total amount of 16S rRNA gene copies determined by qPCR amplicons per gram dry weight is depicted vertically, whereas the cores are shown horizontally. Taxonomic groups with less than 2% abundance are grouped to category others.
Activity and community composition of methanogens
Since bacterial and archaeal OTUs of the original sediments were similar according to diversity analyses, the thermokarst lake sediment cores (one of the duplicate sediment cores taken per sample site) were homogenized and combined prior to incubation. Methanogenic activity at 4°C and 10°C was determined for 279 days in sediment slurries amended with acetate, trimethylamine (TMA), and H2/MeOH, and for 64 days with H2/CO2 (Fig. 2). In all the
Core 1 Core 2
Core 3 Core 4
Core 5 Core 6
Core 7
Core 1 Core 2
Core 3 Core 4
Core 5 Core 6
Core 7
Copy nr per gdw Copy nr per gdw