Oak Ridge National Laboratory

 

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Media Contact: Emma Macmillan ()
Communications and External Relations

 

ORNL biologist 'looks for life in all the wrong places'

OAK RIDGE, Tenn., April 26, 2012 — A scientist finds himself two miles below ground in a gold mine in Africa carrying 40 pounds of equipment and extremely precious bacteria samples. There's a rumble from above and debris trickles off the walls.

No, he's not Indiana Jones in the Temple of Doom. He's Tommy Phelps, ORNL scientist in the Biosciences Division, and he seeks out extreme bacteria for the sake of science in locations such as Africa, Micronesia, Colorado, Virginia and Mississippi.

Phelps has made a career of finding and preserving extremophiles - organisms that thrive in physically and geochemically difficult conditions. The bacteria that Phelps obtains are desirable for a number of reasons. They only grow at super high or low temperatures, are extremely tolerant of metals and salt deposits and are fast growing. Additionally, extremophiles have "sloppy" control over their end products, meaning that researchers can change their conditions, which can alter bacterial metabolism.

These extreme bacteria are essential for a process called nanofermentation, which uses bacteria and sugar to convert salts that contain metal into semiconducting nanoparticles. Because nanofermentation can be used with abundant, low-cost salts as starting materials and sugar as the energy source, the process has the potential to be much cheaper than conventional high- temperature and chemical synthesis routes. Nanofermentation could be used to produce a range of nanoparticles, including metal oxides for batteries, metal-sulfides and selinides for phovoltaic solar cells, superparamagnetic nanoparticles for medical imaging and semiconducting quantum dots for lighting applications.

Before researchers can even think about applications, though, someone has to obtain the bacteria that researchers across the country use for nanofermentation. Although Phelps practices extreme caution in extreme environments, one instance left Phelps fearing for his life.

In 1999, Phelps joined his wife's research project to look for microorganisms in the fractured rocks and deep formation waters in gold mines in South Africa, about two miles underground. After six hours collecting samples, the group was still completing a corehole into the side of a wall.

"I heard a series of pings, felt a concussion wave, and then felt debris fall on my hard hat," Phelps said. "A few minutes later, I heard another set of pings, felt a concussion wave and felt debris fall on my hard hat. When I asked the lead driller what was going on, he said we had missed the elevator we were scheduled to take and workers on the next shift were blasting about 100 meters above us."

The research group waited two hours for the next elevator to arrive and they made it out safely. "When you're working in mines, you have to work within miners' constraints," Phelps said. "If you're deep underground and you're not concerned, there's something wrong. You're a long way from the surface."

Once Phelps obtains samples from these extreme environments, he preserves and ships them to labs across the country. He brings some samples back for Ji Won Moon, ORNL scientist in microbial ecology and physiology, who adds a specific combination of salts and sugars to the bacteria to make a material with ideal properties. Phelps calls Moon a "master of the art " because he can add the perfect ratio of metal salts to bacteria to make a material with either superconducting or magnetic properties.

As Phelps and his colleagues work to perfect the nanofermentation technology, they are planning to scale the process from the laboratory bench to a pilot plant that could provide 200-gallon fermentation batches to make one to three kilogram quantities of nanoparticles, compared with the three to five gallons of culture volume they are using now. Phelps calls himself the "expensive plumber" in the nanofermentation project because he brings the 20 different people across the lab together for the big picture. He's just as involved with the research side as the implementation side as he works with his collaborators to plan the pilot plant on the west end of ORNL's campus and the fermentation vessels.

Although Phelps may downplay his role in advancing nanofermentation technology, he and the team are expanding our understanding of science.

"You're looking for something different," Phelps said. "It's not an adrenaline rush. You're looking for something that could help us understand science and expand horizons."