Methanotrophic activity and diversity in different iSphagnum magellanicum/i dominated habitats in the southernmost peat bogs of Patagonia

摘要

pstrongAbstract./strong iSphagnum/i peatlands are important ecosystems in the methane cycle. Methanotrophs living inside the dead hyaline cells or on the iSphagnum/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 iSphagnum/i dominated bog microhabitats. In contrast to the Northern Hemisphere peat ecosystems the temperate South American peat bogs are dominated by one moss species; iSphagnum magellanicum/i. This permitted a species-independent comparison of the different bog microhabitats. Potential methane oxidizing activity was found in all iSphagnum/i mosses sampled and a positive correlation was found between activity and in situ methane concentrations. Substantial methane oxidation activity (23 ??mol CHsub4/sub gDWsupa??1/sup daysup−1/sup) was found in pool mosses and could be correlated with higher in situ methane concentrations (35 ??mol CHsub4/sub lsupa??1/sup pore water). Little methanotrophic activity (&0.5 ??mol CHsub4/sub gDWsupa??1/sup daysup−1/sup) was observed in living iSphagnum/i mosses from lawns and hummocks. Methane oxidation activity was relatively high (4 ??mol CHsub4/sub gDWsupa??1/sup daysup−1/sup) in iSphagnum/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 ipmo/iA microarray and a complementary ipmo/iA 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 ipmo/iA microarray data indicated that both alpha- and gammaproteobacterial methanotrophs were present in all iSphagnum/i mosses, even in those mosses with a low initial methane oxidation activity. Prolonged incubation of iSphagnum/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 iMethylocystis/i species in the most active mosses suggests that these might be responsible for the bulk of methane oxidation./p.