In a hot spring in Yellowstone National Park, a microbe does something that textbooks say should not be possible: it uses oxygen and sulfur for respiration at the same time. Most organisms pick one, because the two pathways are chemically incompatible and their products interfere with each other. This one appears to have found a way around the conflict.
The ability matters because it lets the microbe exploit fluctuating conditions. Where oxygen is abundant, it breathes aerobically; where sulfur compounds dominate, it can use those instead, and it can apparently blend the two strategies in the transition zones where neither is reliably available. Hot springs shift constantly, so flexibility is a real advantage.
Researchers are now investigating how the organism keeps the two systems from sabotaging each other, which may involve compartmentalisation or careful timing. Beyond the intrinsic interest of the biology, the finding broadens the range of metabolisms astrobiologists consider plausible on other worlds, where the chemical menu may be very different from Earth's.
