Untargeted metabolic profiling of Sphagnum fallax from boreal peatlands identifies antimicrobial compounds and novel metabolites

Peatlands are the most efficient terrestrial ecosystem at storing carbon, which is largely driven by the keystone species Sphagnum. Sphagnum mosses dominate these ecosystems by employing harsh ecosystem tactics to prevent vascular plant growth and microbial degradation of these large carbon stores, therefore in the face of climate variability, it is crucial to understand the chemical structures underlying this carbon sequestration phenomenon. Furthermore, these mosses have recently been shown to contain remarkable and unique compounds with high biological activity, the majority of which remains unknown. High resolution mass spectrometry and liquid state NMR were utilized to provide a comprehensive and novel characterization of the metabolite and lipid profile of Sphagnum fallax from Northern peatlands. A total of 606 putative compounds were detected - 332 novel metabolites and 120 compounds previously unknown to be present in Sphagnum fallax—including, sterols, terpenoids, polyphenols and others. Three fungal metabolites were discovered, including ergosterol, providing insights on fungal colonization that may benefit Sphagnum. Seventeen compounds with previously known antimicrobial activity were detected in Sphagnum fallax, and 232 other possible antimicrobial compounds were identified using network analysis. Taken together, the application of high resolution LC MS/MS, 1H NMR metabolomics and lipidomics enabled the characterization of the metabolite and lipidome profile of Sphagnum fallax, which expanded on previous literature to provide a full characterization of Sphagnum fallax. Understanding the composition of Sphagnum fallax provides a much-needed baseline to begin and pair structure to function in order to understand how Sphagnum acts on its environment, its relation to carbon sequestration in peatlands, and provide key biomarkers to predict peatland C store changes (accumulation, sequestration, emissions) as climate shifts.