Biology Prof Probing The Deep Earth For New Life Forms

SOCORRO, N.M. January 12, 2011 – Dr. Tom Kieft is on a quest to find extremophiles – especially those microbial critters that thrive in the deepest ecosystems on Earth.

Scientists examine a flowing borehole at a research mine in Henderson, Colo.  This scene will be replicated in South Africa during the austral winter when Tech professors Dr. Tom Kieft and Dr. Michael Pullin and student Sarah Hendrickson return for their scientific expedition.

Student researchers take a break in the Witwatersrand Mine in South Africa.

A filtration system set up in a gold mine in South Africa. The initial stages of filtration must be done on site, with further separation and research carried out in laboratories.

Scientists examine a core sample in South Africa. Photos courtesy of Tom Kieft/New Mexico Tech

The New Mexico Tech biology professor has two funded projects, one to explore the deep biosphere in mines in South Africa and one in South Dakota. He is also presenting research at the International Symposium on Deep Subsurface Microbiology in South Africa from January 17 to 24.

Kieft has two deep earth expeditions planned for 2011 – one in South Dakota and one in South Africa.

In addition to the conference in South Africa, Kieft has an ongoing research project in South Africa. In June, he will be joined by Tech chemistry professor Dr. Michael Pullin and Tech master’s student Sarah Hendrickson, each of whom will be presenting research at the conference. The Tech trio will be among the team that drills into the deep earth to find more microbial ecosystems on another trip during June.

“In South Africa, the exciting find is microbial ecosystems that are separate from photosynthesis,” Kieft said. “These organisms get their energy from the products of rock-water interactions.”

Unlike surface and ocean ecosystems that depend on the products of photosynthesis, these extreme, deep Earth bio-systems depend on rock-derived hydrogen, sulfur and other elements as nutrients.

“We have found a new type of ecosystem on Earth,” Kieft said. “These are exciting finds. We’re finding novel life form and so far we know very little about them.”

He said that recent studies have shown that the the majority of biomass on the planet is subsurface – and all of that life is microscopic.

“We want to go to these environments and ask, ‘Who is there?’ and ‘What are they doing?’ and ‘How do they make a living?’” Kieft said.

The known biosphere extends deeper than 3.7 kilometers below the surface, or 11,000 feet, Kieft said. However, the true constraining factor for microbial life is temperature; biologists believe the upper limit that microbes can withstand is about 121 degrees C, or 250 degrees F.

The proposed Deep Underground Science and Engineering Laboratory (DUSEL) in South Dakota has a price tag of about $850 million, with funding to be shared by the National Science Foundation  and the Department of Energy. The bulk of the funding is to be allocated for physics research, but a small percentage is intended for geology and microbiology work. Funded by the National Science Foundation, Kieft and David Bout of the University of Massachusetts are planning to descend to 7,400 feet below the surface in the Homestake Mine in South Dakota, where they’ll drill another 5,000 feet down in search of living organisms.

Scientists are quickly developing an understanding about these microbes. The first microbe to have its genome sequenced is Desulforudis audaxviator.

“This is life in the slow lane, but these organisms still metabolize and change their environment,” he said. “We’ve been working on the subsurface for more than 25 years, but there’s still much more we want to discover.”

Scientists have discovered bacteria and archaea that thrive in these environments. Kieft said further investigations are needed to know if viruses, protozoa or fungi may be able to live in these ecosystems as well.

These strange new life forms in these extreme environments beg several questions of the scientists who are on the trail of these microbes. During a Biology Department seminar in November, Kieft said evolutionary scientists wonder if surface life arose from these subsurface extremophiles. Still more scientists wonder if these non-oxygen environments could serve as analogs for other planets. If life on Earth can exist in environments totally separated from photosynthesis, could other planets such as Mars, where the surface is inhospitable to life, also host subsurface microbial life forms?

A focus of Kieft and Pullin’s latest project is to characterize the dissolved organic carbon in extremely deep ground water.

The researchers have several methods for pulling water from the deep biosphere and extracting the dissolved organic carbon. Kieft said the team uses cartridges to capture the very dilute organic compounds from large volumes of deep groundwater..

Hendrickson is presenting a poster at the Carbon Cycling Conference that compares several methods of extracting organic materials from the groundwater samples.

“Everything has to be uber-careful in an uber-dirty location,” Hendrickson said. “We’re collecting groundwater samples straight out of a borehole.”

The Witwatersrand Deep Microbiology Project operates in existing gold mines, which creates environmental and logistical obstacles for the scientists. Researchers descend to 3 kilometers beneath the surface and walk for a mile or more to reach sites where the miners have drilled into the surrounding rock. Some of the filtration must be done on site, with further extraction done at surface laboratories – either in South Africa or in the United States, Kieft and Hendrickson said.

A first-year master’s student in hydrology, Hendrickson said the various applications of this research are exciting.

“This is a whole different ecosystem that we are seriously undereducated about,” she said. “These bacteria could be on every continent, but we don’t know yet. For the astrobiologists, this could help figure out what we should be looking for on other planets.”

These deep-earth microbes are similar to organisms that thrive around deep-sea hydrothermal vents, but have some characteristics that scientists have never seen before, Hendrickson said.

In addition to discussions of research methods and recent discoveries, the scientists at next week’s conference are also discussing a global network of deep-earth observatories – the Network of Inner Space Observatories – which would include installations on every continent.

– NMT –

By Thomas Guengerich/New Mexico Tech