A tiny yet abundant bacterial group that thrives in the ocean has a massive role in the regulation of our planet's atmosphere and climate, a new study revealed.
The order of bacteria known as Pelagibacterales, which makes up about half a million microbial cells in every teaspoon of seawater, has been found to produce significant amounts of a gas called dimethyl sulfide (DMS), which has vital environmental properties.
Researchers from Oregon State University (OSU) and the University of East Anglia (UEA) believe that molecules of dimethyl sulfide act as cloud condensation nuclei or the seeds that stimulate cloud condensation.
UEA biologist Jonathan Todd, one of the authors of the study, said they examined the bacteria at the molecular genetic level to find out how exactly it generates dimethyl sulfide.
It's all part of a negative feedback loop called the CLAW hypothesis. Under this feedback loop, our planet's atmosphere is stabilized as the sunlight increases the abundance of the marine plankton.
As it turns out, these marine plankton produce a compound called dimethyl sulfoniopropionate (DMSP). The resulting compound is broken down into dimethyl sulfide by the Pelagibacterales, researchers said.
Todd said that through a series of chemical processes, the dimethyl sulfide gas boosts cloud droplets, which in turn reduce the amount of sunlight hitting the surface of the ocean.
Dr. Ben Temperton of University of Exeter, who was a member of the original research team that identified the role of Pelagibacterales in the production of dimethyl sulfide, said the findings of the new study suggests that the bacteria is important in climate stability.
He said improvements in climate models that show how DMS impacts climate must consider the organism as a strong contributor.
Meanwhile, Temperton said what was fascinating about the production of dimethyl sulfide is its "elegance and simplicity."
He said the Pelagibacterales do not have the genetic regulatory mechanisms located in most bacteria. Because the bacteria evolved in oceans with limited nutrients, they have the tiniest genomes of all living organisms. These smaller genomes do not take much time to replicate.
He compared the production of dimethyl sulfide via Pelagibacterales to a pressure valve — when there is too much DMSP for the bacteria to handle, it flows down a pathway that transforms DMS into a waste product.
Todd said the findings of the study may encourage scientists to account for the presence of Pelagibacterales in newer climate models. The details are published in the journal Nature Microbiology.