Untargeted metabolomic profiling of Sphagnum fallax reveals novel antimicrobial metabolites

Abstract

Sphagnum mosses dominate peatlands by employing harsh ecosystem tactics to prevent vascular plant growth and microbial degradation of these large carbon stores. Knowledge about Sphagnum‐produced metabolites, their structure and their function, is important to better understand the mechanisms, underlying this carbon sequestration phenomenon in the face of climate variability. It is currently unclear which compounds are responsible for inhibition of organic matter decomposition and the mechanisms by which this inhibition occurs. Metabolite profiling of Sphagnum fallax was performed using two types of mass spectrometry (MS) systems and 1H nuclear magnetic resonance spectroscopy (1H NMR). Lipidome profiling was performed using LC‐MS/MS. A total of 655 metabolites, including one hundred fifty‐two lipids, were detected by NMR and LC‐MS/MS—329 of which were novel metabolites (31 unknown lipids). Sphagum fallax metabolite profile was composed mainly of acid‐like and flavonoid glycoside compounds, that could be acting as potent antimicrobial compounds, allowing Sphagnum to control its environment. Sphagnum fallax metabolite composition comparison against previously known antimicrobial plant metabolites confirmed this trend, with seventeen antimicrobial compounds discovered to be present in Sphagnum fallax, the majority of which were acids and glycosides. Biological activity of these compounds needs to be further tested to confirm antimicrobial qualities. Three fungal metabolites were identified providing insights into fungal colonization that may benefit Sphagnum. Characterizing the metabolite profile of Sphagnum fallax provided a baseline to understand the mechanisms in which Sphagnum fallax acts on its environment, its relation to carbon sequestration in peatlands, and provide key biomarkers to predict peatland C store changes (sequestration, emissions) as climate shifts.

Antimicrobial Activity of Soil Clostridium Enriched Conditioned Media Against Bacillus mycoides, Bacillus cereus, and Pseudomonas aeruginosa

“…Metabolomics is a high-throughput analytical technique, enabling the identification of low molecular weight metabolites in complex mixtures such as the conditioned media (French et al, 2018;Fudyma et al, 2019;Tang et al, 2020). In this study, we focused on secondary metabolites produced during Clostridium enrichment and their prospective contribution to antimicrobial activity.…”

Morphological and biochemical responses ofSphagnummosses to environmental changes

“…Bryophytes, and more particularly Sphagnum mosses, are vital for peatland C sequestration and storage as they effectively facilitate wet and acidic conditions that inhibits decomposition (Clymo and Hayward, 1982;Rydin and Jeglum, 2013;Turetsky, 2003). Sphagnum mosses also produce a recalcitrant litter and release antimicrobial biochemical compounds in the environment that further hamper the decomposition of dead organic matter (Fudyma et al, 2019;Turetsky, 2003;van Breemen, 1995). However, despite these general properties, we still lack a clear understanding of the species-specific characteristics, or traits, controlling Sphagnum growth and/or survival at global and local scale (Bengtsson et al, 2020a).…”

“…Sphagnum mosses produce thousands of metabolites, and can secrete hundreds of them in their surroundings (Fudyma et al, 2019;Hamard et al, 2019). Like in vascular plants, the role of these compounds in moss physiology and ecology can be either specific or multiple , but all of them play a role in moss fitness and/or tolerance to stress (Isah, 2019;Tissier et al, 2014).…”

“…The regulation of the production of Sphagnum metabolites and of the activity of antioxidant enzymes are likely important processes in shaping Sphagnum morphology, growth, physiology and tolerance to environmental changes. Nowadays, limited number of studies focused on Sphagnum metabolites (Fudyma et al, 2019;Klavina, 2018), while antioxidant enzymatic activities remained unexplored. In addition, the linkages among Sphagnum morphological traits, metabolites and antioxidants are virtually unknown, while resource allocation among these different Sphagnum attributes could have important ramifications for peatland carbon cycling.…”

Rewiring of peatland plant-microbe networks outpaces species turnover

“…Indeed, peatland plants, and Sphagnum mosses in particular, produce recalcitrant litter (Clymo 1965, Dorrepaal et al 2005) and release anti-microbial compounds (Fudyma et al 2019;Hamard et al 2019), which together with acidic and anoxic environmental conditions impede microbial breakdown of organic matter and thus facilitate the accumulation of plant remains. Hence, the C sink function of peatlands is controlled by an interplay between abiotic and biotic factors.…”