Methanotrophic activity and diversity in different Sphagnum magellanicum dominated habitats in the southernmost peat bogs of Patagonia

N. Kip, C. Fritz, E. S. Langelaan, Y. Pan, L. Bodrossy, V. Pancotto, M. S. M. Jetten, A. J. P. Smolders, H. J. M. Op den Camp
2012 Biogeosciences  
<p><strong>Abstract.</strong> <i>Sphagnum</i> peatlands are important ecosystems in the methane cycle. Methanotrophs living inside the dead hyaline cells or on the <i>Sphagnum</i> mosses are able to act as a methane filter and thereby reduce methane emissions. We investigated in situ methane concentrations and the corresponding activity and diversity of methanotrophs in different <i>Sphagnum</i> dominated bog microhabitats. In contrast to the Northern Hemisphere peat ecosystems the temperate
more » ... th American peat bogs are dominated by one moss species; <i>Sphagnum magellanicum</i>. This permitted a species-independent comparison of the different bog microhabitats. Potential methane oxidizing activity was found in all <i>Sphagnum</i> mosses sampled and a positive correlation was found between activity and in situ methane concentrations. Substantial methane oxidation activity (23 μmol CH<sub>4</sub> gDW<sup>−1</sup> day<sup>&amp;minus;1</sup>) was found in pool mosses and could be correlated with higher in situ methane concentrations (>35 μmol CH<sub>4</sub> l<sup>−1</sup> pore water). Little methanotrophic activity (&amp;lt;0.5 μmol CH<sub>4</sub> gDW<sup>−1</sup> day<sup>&amp;minus;1</sup>) was observed in living <i>Sphagnum</i> mosses from lawns and hummocks. Methane oxidation activity was relatively high (>4 μmol CH<sub>4</sub> gDW<sup>−1</sup> day<sup>&amp;minus;1</sup>) in <i>Sphagnum</i> litter at depths around the water levels and rich in methane. The total bacterial community was studied using 16S rRNA gene sequencing and the methanotrophic communities were studied using a <i>pmo</i>A microarray and a complementary <i>pmo</i>A clone library. The methanotrophic diversity was similar in the different habitats of this study and comparable to the methanotrophic diversity found in peat mosses from the Northern Hemisphere. The <i>pmo</i>A microarray data indicated that both alpha- and gammaproteobacterial methanotrophs were present in all <i>Sphagnum</i> mosses, even in those mosses with a low initial methane oxidation activity. Prolonged incubation of <i>Sphagnum</i> mosses from lawn and hummock with methane revealed that the methanotrophic community present was viable and showed an increased activity within 15 days. The high abundance of methanotrophic <i>Methylocystis</i> species in the most active mosses suggests that these might be responsible for the bulk of methane oxidation.</p>
doi:10.5194/bg-9-47-2012 fatcat:sdmjvwvfbbc4ra6zilsxpzulcy