https://www.quantamagazine.org/the-cells-that-breathe-two-ways-20250723/
...
Instead of using oxygen to harvest energy, many
single-celled life-forms that live in environments
far from oxygen’s reach, such as deep-sea
hydrothermal vents or stygian crevices in the
soil, wield other elements to respire and unlock
energy.
This physical separation of the oxygen-rich and
oxygen-free worlds is not merely a matter of life
utilizing available resources; it’s a biochemical
necessity. Oxygen doesn’t play nice with the
metabolic pathways that make it possible to
respire with the use of other elements, such as
sulfur or manganese. It gives aerobes like us
life, but for many anaerobes, or creatures that
respire without oxygen, oxygen is a toxin that
reacts with and damages their specialized
molecular machinery.
...
An ongoing mystery for researchers is how life
navigated the shift from anaerobic to aerobic
respiration; so much microbial biodiversity had
to adapt to a world filled with what was once a
biochemical bane. Now researchers have fresh
insight into what that transition could have
looked like billions of years ago, gleaned from
an organism living today. A bacterium that
researchers collected from the cauldron of a
Yellowstone National Park hot spring does
something that life really shouldn’t be able to
do: It runs aerobic and anaerobic metabolisms
simultaneously. It breathes oxygen and sulfur
at the same time.
...
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