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

作为大气甲烷的最大天然来源，泥炭地储存了超过30%的陆地碳(Rodhe，1990；Gorham，1991；Hein等人，1997)，大部分碳来自泥炭苔藓和互惠共生的甲烷营养细菌群落(图1)(Cymo和Hayward，1982，Raghoebarsing等人)。2005年；)。然而，由于人类活动和气候变暖，全球超过15%的泥炭地遭到破坏。尤其是在英国，只有不到20%的泥炭地幸存下来(贝恩等人，2011年)。英国介绍了旨在重新湿润泥炭地和在受损地区重新种植泥炭苔藓的恢复项目。先前的研究表明，当Beadamoss可持续生长的Sphagnum Moss(BeadaHumok)用于恢复自然泥炭地时，泥炭地的甲烷排放显著减少(Ksithtley，2020)，然而，尚未表明甲烷营养细菌是否与微繁殖的泥炭藓有关。在我的硕士论文项目中，我展示了BeadaHumok甚至在天然泥炭地适应进化之前就积极地直接降解温室中的甲烷，并显示出与天然泥炭地生长的泥炭苔藓类似的降解甲烷的能力。我鉴定了一些相关的甲烷营养细菌，它们主要是甲氧菌属、甲氧菌属、甲氧菌属和甲氧菌属。该项目的总体目标是描述泥炭地恢复过程中与可持续生长的泥炭苔藓相关的甲烷养殖菌的结构和生态生理学，重点是温室生长系统中甲烷养生菌的维持，以及恢复前后甲烷养殖菌种群的变化。该项目有以下目标：利用依赖于栽培的方法(分离)和独立的方法(功能遗传标记和元组学方法)，测定温室内可持续生长的不同泥炭苔藓的甲烷氧化潜力，并鉴定相关的甲氧菌。研究与泥炭藓相关的甲氧菌的生态生理学，以评估它们利用非甲烷底物的能力(兼性甲烷化)，研究甲氧菌与苔藓的相互作用(甲氧菌降解甲烷的能力；泥炭苔藓的光合作用能力)。在修复项目中使用苔藓之前，开发一种‘质量控制程序’来确定甲烷氧化菌的存在和活性。在恢复项目中，评估泥炭苔藓建立后沼泽中是否保留了与苔藓相关的甲氧菌。我们将设计一个泥炭地中隔，以模拟泥炭苔藓的自然生长环境(如Kox等人所做的)。(2021年)，并用气相色谱测定甲烷降解速率。将使用针对dna、rna和蛋白质的分子方法，包括定量聚合酶链式反应和metagenomic/metatranscriptomics/metaproteomics.，来确定与甲烷相关的厌氧菌的多样性和活性。与13C标记底物的稳定同位素培养将用于确定潜在兼性甲烷氧化菌的底物范围。此外，我们亦会进行甲烷氧化菌的分离工作。我们会利用通过量测序的方法，研究甲烷氧化菌在泥炭苔藓中的定植和分布，并将这些方法应用于泥炭地在泥炭地移植泥炭苔藓前后的修复工程。

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.