A recent analysis of the micro-organisms that inhabit deep-sea hydrothermal vents reveals that these organisms survive on energy received from chemical reactions with components of rocks or dissolved substances in water. According to a study from the University of Massachusetts Amherst, a team led by biologist James Holden has recently discovered that the growth of the high-temperature methanogens depends on the hydrogen and carbon dioxide content in the superheated deep-sea vents.
Moreover, Holden believes that the evidence indicates that the micro-organisms living in the crust and marine sediments could total the number of animals and plants on the surface.
"Evidence has built over the past 20 years that there's an incredible amount of biomass in Earth's subsurface, in the crust and marine sediments, perhaps as much as all the plants and animals on the surface. We're interested in the microbes in the deep rock, and the best place to study them is at hydrothermal vents at undersea volcanoes. Warm water flows bring the nutrient and energy sources they need," Holden wrote.
The present research will help scientist understand the metabolic processes on Earth billions of years ago. A team of scientists used research submarine Alvin and collected hydrothermal fluids flowing from black smokers up to 350 degrees C (662 degrees F) from Axial Volcano and the Endeavour Segment. The long-term observatory sites are situated along an undersea mountain range about 200 miles off the coast of Washington and Oregon and 1-1.5 miles below the surface.
"Models have predicted the habitability of the rocky environments that we're most interested in, but we wanted to ground truth into these models and refine them," Mr. Holden explains.
"We hypothesized that the methanogens grow syntrophically with the hydrogen producing microbes, and it worked out that way in the lab with a strain from the site. So we have described a methanogen ecosystem that includes a symbiotic relationship between microbes, which in my mind highlights the strength of our multi-pronged team approach. It really paid off. We feel that more research coupling broad field measurements with laboratory experiments will be really fruitful in the future," Holden added.
The report was published in the Proceedings of the National Academy of Sciences.
