Polyphenols, a diverse group of organic compounds produced by plants, have been found to be toxic to microorganisms. In peatlands, it was previously believed that microorganisms avoided this toxicity by breaking down polyphenols using an enzyme that relies on oxygen.
However, in low-oxygen environments such as those following climate-induced thawing, this enzyme becomes inactive, leading to the accumulation of polyphenols. This accumulation inhibits the carbon cycling process of microbes.
In a recent study, researchers analyzed data from thousands of microbial genomes obtained from Stordalen Mire, an Arctic peatland in Sweden. They discovered that the microorganisms in this environment utilized alternative polyphenol-active enzymes that function both with and without oxygen.
This study emphasizes the critical role of polyphenols in peatland carbon dynamics and suggests that the carbon stored in these ecosystems is more vulnerable to release into the atmosphere due to climate change than previously believed.
Arctic peatlands are crucial carbon reservoirs, but the stability of this stored carbon is under threat as global temperatures rise. Recent research into the soil microbiome of Arctic peatlands has revealed a surprising finding: many microorganisms metabolize polyphenols, a previously overlooked component of carbon storage. This new understanding equips scientists with vital insights for predicting the impacts of climate change on Arctic ecosystems and developing targeted mitigation strategies.
Peatlands have always fascinated scientists as crucial carbon reserves, but the role of microorganisms in carbon cycling has been a mystery. This new research challenges the idea that peatland microorganisms only break down polyphenols in the presence of oxygen using phenol oxidase.
Drawing from insights from oxygen-limited environments like the human gut and rumen, where alternative enzymes and pathways break down polyphenols, the research team developed a novel computational tool to quickly analyze polyphenol metabolisms in microbial genomes.
Applied to thousands of microbial genomes from an Arctic peatland, this software revealed a surprising diversity of polyphenol-transforming pathways. Some microorganisms were found to possess a multitude of these genes, indicating a strong ability to degrade polyphenols. Additionally, the findings underscore the adaptability of microbial gene expression to changes in soil redox conditions across the landscape.
This groundbreaking research unveils previously unknown biochemistry, marking a significant leap in our comprehension of carbon cycling in these crucial ecosystems. These findings not only enhance our understanding of microbial metabolism but also emphasize the complex interaction between microorganisms and carbon dynamics in the context of climate change.
Journal reference:
- Bridget B. McGivern, et al. Microbial polyphenol metabolism is part of the thawing permafrost carbon cycle. Nature Microbiology, 2024; DOI: 10.1038/s41564-024-01691-0
