From nutrients to signaling molecules: DOP metabolism drives aerobic methane production under phosphorus limitation

The phenomenon of the 'marine CH₄ paradox' occurs in ocean surface waters that are oxygen-rich yet supersaturated with CH₄, challenging the traditional anaerobic methanogenesis pathways. Notably, many oxygenated and phosphorus-limited lakes commonly exhibit significant phosphorus (P) limitation and a potentially enhanced trend of dissolved organic phosphorus (DOP) utilization. Their nutrient characteristics show convergence with surface ocean waters, suggesting that the 'DOP-CH₄' metabolic pathway might also exist in oxygenated and phosphorus-limited lakes. Supported by the detection of functional genes (e.g., phnJ) and observational evidence of relatively enriched δ¹³CH₄ signals, this paper proposes a conceptual framework: 'P-limited water bodies → enhanced DOP utilization → C-P lyase expression → aerobic CH₄ production and release.' This mechanism has the potential to extend to all water bodies with similar nutrient structures. Based on this study, the role of DOP is reevaluated. Future ecological model construction urgently needs to incorporate such metabolic signaling molecules into frameworks to explore their pivotal role in the chain linking microbial ecological regulation, GHGs emissions, and responses to global change.