Page 213 - Microbial methane cycling in a warming world From biosphere to atmosphere Michiel H in t Zandt

Assimilatory nitrate reduction genes (assimilatory nitrate reductase catalytic subunit nasA, and assimilatory nitrate reductase narB) show a general decrease. Denitrification and dissimilatory nitrate reduction to ammonium (DNRA) genes (iron-containing nitrite reductase nrfA, copper- containing nitrite reductase nirK, and nitrous oxide reductase nosZ) also show a general decrease in all samples. In contrast, nitric oxide reductase subunit beta (norB) shows an increase in all samples, with the strongest response in PF. The norB gene carrier was primarily associated with Proteobacteria and Bacteroidetes, with increasing abundance of Bacteroidetes-associated in contrast to decreasing Proteobacteria-associated sequences after long-term warming (Fig. S5). For nitrogen fixation a decrease of nitrogenase reductase (nifH) was observed for AL, whereas an increase was observed for TL and PF. Nitrogen fixation was mainly associated with members of the Proteobacteria (>92% of hits).
Figure 6. Heatmap of key genes involved in carbon, nitrogen, and sulfur cycling of anoxic ecosystems. The relative abundance is given in transcripts per million (TPM) for the active layer (AL), transition layer (TL), and permafrost (PF).
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