Moore Foundation grantees at the Woods Hole Oceanographic Institution and the University of Hawaii may have solved a longstanding question in marine microbiology: where does the methane found on the surface of our oceans come from, given microbes that generate methane can't actually survive at the surface?
The answer to this "marine methane paradox," says WHOI geochemist Dan Repeta, is the complex ways that bacteria break down dissolved organic matter, a cocktail of substances excreted into seawater by living organisms.
In a recent issue of Nature Geoscience, Repeta and colleagues David Karl and Edward DeLong describe how much of the ocean’s dissolved organic matter is made up of novel polysaccharides — long chains of sugar molecules created by photosynthetic bacteria in the upper ocean.
Bacteria begin to slowly break these polysaccharides, tearing out pairs of carbon and phosphorus atoms from their molecular structure. In this process, the microbes create methane, ethylene and propylene gasses as byproducts. Most of the methane escapes back into the atmosphere.
The research team’s findings describe a totally new pathway for the microbial production of methane in the environment, that is very unlike all other known pathways.
Leading up to this study, researchers like Repeta had long suspected that microbes were involved in creating methane in the ocean, but were unable to identify the exact ones responsible.
"All the pieces of this puzzle were there, but they were in different parts, with different people, in different labs, at different times," says Repeta. "This paper unifies a lot of those observations."
This work was funded through the foundation's Marine Microbiology initiative.
Read the full article here.
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