It has long been known that there are vast deposits of methane under the sea floor, generated by the decay of animal and plant carcasses. What has not been well-understood, though, is how this methane didn’t make it to the atmosphere.
Methane, as a greenhouse gas, is about 400 times more powerful than carbon-dioxide, so even small amounts of methane released from the sea floor could have catastrophic consequences for the atmosphere.
In the oxygen-depleted depths of the ocean, anaerobic oxidation of methane [AOM] prevents the release of the potent gas into the atmosphere, and it was found that two microorganisms were closely associated with AOM, working in conjunction to metabolize methane.
Recently, though, researchers at the Planck Institute for Marine Microbiology, along with colleagues in Vienna and Mainz, found that a single microorganism, of the Archaea domain, performs AOM to digest methane and give off sulfur as a waste product, which the other closely related bacterium feeds off of.
“Using chromatographic and state-of-the-art spectroscopic techniques we found surprisingly high concentrations of elemental sulfur in our cultures,” says Professor Marcel Kuypers, of the Planck Institute. “The single-cell techniques showed that the sulfur content in the methane-degrading archaeon was much higher than in the bacterium. Our experiments show that this sulfur is formed during sulfate respiration.”