The potential importance of methylated substrates in methane production within three northern Minnesota peatlands. (November 2020)

• Record Type: Journal Article
• Authors: Hanna, Emily; Keller, Jason K.; Chang, Daniel; de Bruyn, Warren; Zalman, Cassandra
• Is Part Of: Soil biology and biochemistry. Volume 150(2020)
• Publication Date: 2020-11
• Subjects: Isotope -- Methane -- Methylotrophic -- Peatlands; Soil biochemistry -- Periodicals; Soil biology -- Periodicals; Sols -- Biochimie -- Périodiques; Sols -- Biologie -- Périodiques; Sols -- Microbiologie -- Périodiques; Bodembiologie; Biochemie; 631.46
• DOI: 10.1016/j.soilbio.2020.107957
• Languages: English
• ISSNs: 0038-0717

Abstract

Abstract: Peatlands store close to half of the terrestrial soil carbon and release substantial amounts of the greenhouse gas methane (CH4 ) to the atmosphere. While CH4 is thought to be produced mainly by hydrogenotrophic and acetoclastic methanogenic pathways, methylotrophic methanogenesis may be a hidden, yet potentially important, source of CH4 in these globally significant ecosystems. To explore the importance of methylotrophic methanogenesis in northern peatlands, 13 C-labeled methylated substrates (methanol, dimethylsulfide, and trimethylamine) were added to soils along a depth profile and the production of 13 C–CH4 was measured. Additionally, the concentrations of methylated compounds were measured across a soil depth profile in situ. Results suggest that methylated substrates can be used by peatland microbes, resulting in CH4 production in all sites at all depths. Methanol was converted to CH4 in each site at all depths. In contrast, trimethylamine and dimethylsulfide were only converted to CH4 at the surface depth regardless of site. In situ concentrations of dimethylsulfide were below detection limit in all sites and depths. Monomethylamine and methanol were present in situ with concentrations ranging from 30 to 1225 nM. For the first time in peatlands, we have estimated contributions of methylated substrates to the total CH4 produced. Microbial processing of methylated substrates contributed a maximum of 11% of the total CH4 produced at depth in one peatland; but, in shallow soils with higher rates of CH4 production, the potential contribution of methylotrophic methanogenesis to overall CH4 production was minor. Highlights: Methylotrophic methanogenesis is possible through the depth profile in three peatlands. Utilization of methylated substrates contributes a maximum of ~11% of CH4 production in the studied soils. Methanol and monomethylamine are dominant methylated substrates in situ .