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Could extreme Earth microbes pave way for discovery of life on Mars?

According to a release from the University of Massachusetts Amherst, a team led by biologist James Holden has recently performed an analysis of the microorganisms that inhabit deep-sea hydrothermal vents.

While most life lives on or near the surface and receives energy directly or indirectly from the Sun, there is also a significant port of life on Earth which dwells in places deep underground or under the sea. These organisms typically survive on energy obtained from chemical reactions with components of rocks or dissolved substances in water.

James Holden, leader of the team that conducted the study, says, “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. 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’s team looked specifically at the organisms which survive in the high temperatures of undersea volcanic vents and survive on chemical reactions which produce methane. Using reactors in laboratories, the team studied the requirements the organisms had for survival and growth, finding the minimum amounts of hydrogen concentration necessary for survival. “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.

The team also studied samples coming from actual underwater vents. After using the research submarine Alvine to collect samples of fluids flowing from undersea vents near Oregon and Washington, the team analyzed the fluids to characterize their chemical and biological contents. David Butterfield, a member of the study and a researcher from the University of Washington, said, “This is an effort to understand the biological and chemical factors that determine microbial community structure and growth rates.”

Dr. Holden describes the study as similar to more familiar biological work, but done on a little-known ecosystem. “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. It’s very exciting, and will advance our understanding of biogeochemical cycles in the deep ocean.”

In a very different environment, NASA’s Curiosity rover has begun its search for life at Gale Crater. After landing on the red planet Sunday night and taking several stunning images of its new surroundings, Curiosity will look for “the ingredients of life.”

The findings are published in the Proceedings of the National Academy of Sciences.