Oxidative metabolisms catalyzed Earth's oxygenation.

Area of Science:

• Geochemistry
• Biogeochemistry
• Evolutionary Biology

Background:

• Organic carbon burial is a key driver of Earth's atmospheric oxygenation.
• A paradox exists where increased oxygen levels may inhibit organic carbon burial.

Purpose of the Study:

• To resolve the oxygenation paradox by proposing a new hypothesis.
• To investigate the role of partially oxidized organic matter (POOM) in carbon burial.
• To link biological innovations with geological changes in Earth's oxygenation.

Main Methods:

• Developed a mathematical model to support the POOM hypothesis.
• Reconstructed the evolutionary history of flavin-dependent Baeyer-Villiger monooxygenases.
• Correlated enzyme evolution with Proterozoic and Phanerozoic atmospheric oxygenation events.

Main Results:

• Partially oxidized organic matter (POOM) enhances organic carbon burial through mineral interactions.
• The diversification of key enzymes generating POOM aligns temporally with major oxygenation events.
• Oxidative metabolisms created a positive feedback loop, amplified by geological changes.

Conclusions:

• Earth's oxygenation is an autocatalytic process driven by biological and geological factors.
• Partially oxidized organic matter (POOM) plays a crucial role in early Earth oxygenation.
• Evolutionary expansion of oxidative metabolisms facilitated a self-amplifying oxygenation transition.