August 7, 2012
Microbial Life In Undersea Volcanoes Provide Exciting New Research Opportunities
Brett Smith for redOrbit.com - Your Universe Online
Although some have estimated a third of the Earth's biomass lives in our planet's rocks and sediments, little is known about these hard to reach organisms.
A new report published in the Proceedings of the National Academy of Sciences (PNAS), with possibly wide reaching implications, looks to study one group of methane-producing microbes that live deep in the cracks of hot undersea volcanoes.
Because of the alien nature of these organisms, the study could also equate their metabolic processes to those that existed on Earth 3 billion years ago and that of extraterrestrial microbes living on other planets.
Researchers also attempted to illuminate the processes behind terrestrial natural gas formation, since these microbes take in hydrogen and carbon dioxide to produce methane as a waste product.
"Evidence has built over the past 20 years that there's an incredible amount of biomass in the Earth's subsurface in the crust and marine sediments, perhaps as much as all the plants and animals on the surface,” said study co-author James Holden, a microbiologist at the University of Massachusetts in Amherst.
“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."
"Just as biologists studied the different habitats and life requirements for giraffes and penguins when they were new to science, for the first time we're studying these subsurface microorganisms, defining their habitat requirements and determining how those differ among species,” he added.
Samples used in the study were taken from Axial Volcano and the Endeavour Segment using the research submarine Alvin. The scientists collected hydrothermal fluids from volcanic “smokers” up to 660 degree Fahrenheit and sea floor cracks at slightly lower temperatures. These sites were located about 200 miles off the northwest American coast and more than a mile below the ocean's surface.
Back at UMass Amherst, the scientists used a two-liter bioreactor to control hydrogen levels for their growing sample cultures. As a control, the team also cultured commercially available hyperthermophilic methanogen species. They found that when both sets of organisms were given the same amounts of hydrogen and identical growth conditions, they grew at the same rates.
While Holden and Helene Ver Eecke at UMass Amherst cultured the naturally occurring organisms, Julie Huber at the Marine Biological Laboratory on Cape Cod provided molecular analyses of the microbes. Meanwhile, David Butterfield and Marvin Lilley at the University of Washington analyzed the geochemical fluid that was sampled along the ocean floor.
After the initial analysis, the team found that microbes collected from the low-hydrogen Endeavour site, feed on the hydrogen waste produced by the other hyperthermophiles living alongside them.
"This was extremely exciting," said Holden. "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."