![[LEFT] Occurrence of bd-type oxygen reductase in a dated tree of life. Branches in the dated tree of life obtained from Mahendrarajah et al. [81] are colored according to the presence (turquoise) or absence (gray) of bd-type oxygen reductase. Eukaryotes were not included in the analysis and are therefore colored in higher gray tones, as are taxa that were not present in the comparative dataset. Dark blue dots at nodes represent possible origins of bd-type oxygen reductase. Purple bars represent the percentage of strains within the taxa that have reductases. [RIGHT] Occurrence of HCO oxygen reductase in a dated tree of life. Branches in the dated tree of life obtained from Mahendrarajah et al. [81] are colored according to the presence (yellow) or absence (gray) of HCO oxygen reductase. Eukaryotes were not included in the analysis and are therefore colored in higher gray tones, as are taxa that were not present in the comparative dataset. Brown dots at nodes represent possible origins of HCO oxygen reductase. Purple bars represent the percentage of strains within the taxa that have reductases. -- Biochimica et Biophysica Acta (BBA) - Bioenergetics](https://i0.wp.com/astrobiology.com/wp-content/uploads/2026/03/Oxygen-Reductase-Origin-Followed.png?resize=1200%2C900&ssl=1)
The history of Earth’s atmospheric oxygen is a cornerstone of evolutionary biology. While unequivocal evidence for an increase in atmospheric O2 marks the Great Oxidation Event (GOE) roughly 2.4 billion […]
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