Mitigation of Methane Emissions from Peatlands - a Role for Micro-propagated Sphagnum-Associated Methanotrophs

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As the largest natural source of atmospheric methane, peatlands store over 30% of terrestrial carbon (Rodhe, 1990; Gorham, 1991; Hein et al., 1997), most of the carbon comes from Sphagnum mosses and mutually beneficial symbiotic methanotrophic bacteria community (Figure 1) (Clymo and Hayward, 1982, Raghoebarsing et al. 2005;). However, more than 15% of peatlands have been destroyed globally due to human activities and climate warming. Especially in the UK, less than 20% of peatlands survived (Bain et al., 2011). Restoration projects aiming to rewet peatland and replant Sphagnum moss in damaged areas was presented in the UK. Prior research has shown that methane emissions from peatlands are significantly reduced when Beadamoss sustainably grown Sphagnum moss (BeadaHumok) is used to restore natural peatlands (Keightley, 2020), however, it has not been shown whether methanotrophic bacteria are associated with micropropagated Sphagnum. In my MSc dissertation project, I demonstrated that BeadaHumok actively degrades methane straight from the greenhouse even before adaptive evolution in natural peatland and showed similar ability to degrade methane compared to Sphagnum mosses grown in natural peatland. I identified some of the associated methanotrophic bacteria, they were dominated by the genera Methylocystis, Methylosinus, Methylocapsa and Methylocella.The overall aim of the project is to characterise the structure and ecophysiology of methanotrophs associated with sustainably grown Sphagnum moss during peatland restoration, with emphasis on the maintenance of methanotrophs in the greenhouse growing system, and changes in methanotroph populations before and after restoration. The project has the following objectives:Determine methane oxidation potential and identify associated methanotrophs of different Sphagnum mosses grown sustainably by micropropagation in the greenhouse using cultivation-dependent (isolation) and -independent approaches (functional genetic markers and meta-omics approaches)Study the ecophysiology of Sphagnum-associated methanotrophs to evaluate their capability for using non-methane substrates (facultative methanotrophy)Investigate the interaction of methanotrophs and mosses (ability of methanotrophs to degrade methane; photosynthetic capacity of Sphagnum mosses).Development of a 'quality control' procedure to determine presence and activity of methanotrophs prior to use of mosses in restoration projects.Assess whether moss-associated methanotrophs are maintained in the bogs post establishment of Sphagnum moss in restoration projects.We will design a peatland mesocosm for simulating the natural growth environment of Sphagnum moss (as by Kox et al. (2021) and measure the rate of degradation of methane by gas chromatography.The diversity and activity of Sphagnum associated methanotrophs will be determined using molecular methods targeting DNA, RNA and protein, including quantitative PCR, and metagenomic/metatranscriptomics/metaproteomics. Stable isotope incubations with 13C labelled substrates will be used to determine the substrate range of potentially facultative methanotrophs present. Isolation of methanotrophs will also be carried out.We will use throughput sequencing to develop methods to detect the colonisation and distribution of methanotrophs in Sphagnum moss and apply these to peatland restoration projects before and after transplantation of Sphagnum mosses.