The study investigates the role of microbial polyphenol metabolism in the thawing permafrost carbon cycle. Using a multi-omics approach, the researchers examined the relationship between phenol oxidase expression and saturation in Stordalen Mire, a model Arctic peatland. They found no significant negative relationship between phenol oxidase activity and water saturation, nor between phenol oxidase expression and polyphenol concentrations. Instead, they observed a positive correlation between polyphenol abundance and porewater CO₂ concentrations, indicating that polyphenols may contribute to soil respiration. The researchers developed CAMPER, a gene annotation tool, to identify polyphenol-active enzymes in microbial lineages under various redox conditions. They identified diverse polyphenol transformation pathways expressed by various microbial lineages, challenging the enzyme latch theory that polyphenols inhibit microbial carbon decomposition in saturated soils. The study highlights the need to consider both oxic and anoxic polyphenol metabolisms to understand carbon cycling in changing ecosystems.The study investigates the role of microbial polyphenol metabolism in the thawing permafrost carbon cycle. Using a multi-omics approach, the researchers examined the relationship between phenol oxidase expression and saturation in Stordalen Mire, a model Arctic peatland. They found no significant negative relationship between phenol oxidase activity and water saturation, nor between phenol oxidase expression and polyphenol concentrations. Instead, they observed a positive correlation between polyphenol abundance and porewater CO₂ concentrations, indicating that polyphenols may contribute to soil respiration. The researchers developed CAMPER, a gene annotation tool, to identify polyphenol-active enzymes in microbial lineages under various redox conditions. They identified diverse polyphenol transformation pathways expressed by various microbial lineages, challenging the enzyme latch theory that polyphenols inhibit microbial carbon decomposition in saturated soils. The study highlights the need to consider both oxic and anoxic polyphenol metabolisms to understand carbon cycling in changing ecosystems.