The researchers discovered that underwater mussels found in deep-sea hydrothermal vents house symbiotic bacteria that use hydrogen as energy source.
The researchers were studying the deep-sea mussel species the Bathymodiolus puteoserpentis, a common species in the Logatchev hydrothermal vent field. Logatchev is around 3000 meters deep and located between the Caribbean and Cape Verde Islands.
Organisms that thrive in hydrothermal vents, formed when tectonic plates drift apart and magma rises and interacts with seawater, survive through symbiotic relationships with chemosynthetic microbes.
At hydrothermal vents, seawater interacts with the hot rock and magma, becoming superheated and dissolving minerals and delivering inorganic compounds such as hydrogen sulfide, ammonium, methane, iron and hydrogen into the oceans. The chemosynthetic microbes oxidize these compounds for energy.
Earlier discoveries found out that there are sulfur-oxidizing microbes and methane-oxidizing microbes that make use of hydrogen sulfide and methane, respectively.
The researchers found that the symbiont microbes in the mussels used third energy source and were able to oxidize hydrogen. They obtained samples from mussel beds and identified the mussel symbiont hydrogenase, the enzyme for hydrogen oxidation using molecular techniques.
"The hydrothermal vents along the mid-ocean ridges that emit large amounts of hydrogen can therefore be likened to a hydrogen highway with fuelling stations for symbiotic primary production," said Jillian Petersen, a researcher.
The researchers noted that at Logatchev, the highest hydrogen concentrations ever measured at hydrothermal vents were recorded, making it ideal for hydrogen oxidizing organisms.
"Our calculations show that at this hydrothermal vent, hydrogen oxidation could deliver seven times more energy than methane oxidation, and up to 18 times more energy than sulfide oxidation," added Ms. Petersen.
The researchers also found that the symbionts of other hydrothermal vent animals such as the giant tubeworm Riftia pachyptila and the shrimp Rimicaris exoculata share the key gene for hydrogen oxidation that the mussel has.
The team was lead by Nicole Dubilier of the Max Planck Institute of Marine Microbiology and supported by the Max Planck Society, the German Research Foundation as well as MARUM. A paper on the results of the study "Hydrogen is an energy source for hydrothermal vent symbioses" was published in the current issue of Nature. (Kristin Dian Mariano)
source: APEC-VC
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