These Newly Discovered Cells Breathe in Two Ways

"They already knew it could use oxygen, so they tested other combinations in the lab. When oxygen was absent, RSW1 could process hydrogen gas and elemental sulfur-chemicals it would find spewing from a volcanic vent-and create hydrogen sulfide as a product. Yet while the cells were technically alive in this state, they didn't grow or replicate. They were making a small amount of energy-just enough to stay alive, nothing more."

""The cell was just sitting there spinning its wheels without getting any real metabolic or biomass gain out of it," Boyd said. Then the team added oxygen back into the mix. As expected, the bacteria grew faster. But, to the researchers' surprise, RSW1 also still produced hydrogen sulfide gas, as if it were anaerobically respiring. In fact, the bacteria seemed to be breathing both aerobically and anaerobically at once, and benefiting from the energy of both processes."

Researchers experimentally tested substrate use by a bacterial strain, RSW1. Without oxygen, RSW1 oxidized hydrogen gas and elemental sulfur from vents to produce hydrogen sulfide but did not grow or replicate, generating minimal energy for maintenance. Reintroducing oxygen increased growth rate, yet RSW1 continued producing hydrogen sulfide, appearing to perform aerobic respiration and anaerobic sulfur-based respiration concurrently. The cells benefited from energy from both processes, indicating a hybrid metabolism. Such simultaneous opposing metabolic modes are unexpected because oxygen exposure usually induces damaging reactive oxygen compounds in anaerobes; RSW1 appears to avoid that stress.

Read at WIRED