Fig. 4: Conceptual reframing of polyphenols in peatland systems.
From: Microbial polyphenol metabolism is part of the thawing permafrost carbon cycle
a, The enzyme latch model posits that polyphenols can only be degraded by phenol oxidases under oxic conditions. Without oxygen, polyphenols accumulate and generally inhibit the microbial community, subsequently shutting down microbial metabolism, reducing CO2 and CH4 emissions. b, In this study, we propose a polyphenol-cognizant model that accounts for the fact that polyphenols are a diverse group of compounds with diverse metabolic impacts. Microbial communities encode and express multiple substrate-specific enzymes for diverse polyphenols, with strategies under both oxic and anoxic conditions. As a whole, the microbial community exhibits a gradient of responses to polyphenols, ranging from potential inhibition to stimulation. Due to this, polyphenols are integrated into carbon cycling networks, with susceptible organisms, tolerant organisms and stimulated organisms.
