Chan, above, said she's excited about the collaborative
community at UD. Photo by Scott Brown.
Pictured below is an orange bacterial mat
from the Wisconsin mine. Photo by Tom O'Conner
You might not think a flooded mine in Wisconsin could have anything in common with an underwater volcano off Hawaii. But that’s exactly what researcher Clara Chan has discovered.
Both locations are home to large communities of bacteria — sprawling orange mats of life that look a lot like pumpkin pulp — that thrive on iron entering the water through cracks in the earth’s surface. Chan, who will join the College of Marine and Earth Studies (CMES) in January as an assistant professor of geological science, began working on the bacteria from the mine for her dissertation at the University of California, Berkeley.
“You’ve heard a lot about environmental problems caused by mine drainage and heavy metals being released,” she said. “That was not a problem in this mine.”
The metal concentrations in the water coming out of the mine all tested below EPA standards, she explained. Upon testing the bacterial mats, however, Chan learned that they were high in concentrations of iron and heavy metals such as lead and arsenic. That’s because the bacteria metabolize iron to create energy, making nanometer-size rust-like minerals in the process. These minerals have extremely high surface area that attracts heavy metals, efficiently removing them from the groundwater.
Chan, who continues to research the orange mats, identifies the microbes and studies how they control the chemistry of the water in their habitat. To do that, she grows iron-oxidizing microbes in the lab and studies their metabolic processes and the minerals they create as by-products. By looking at the minerals at micron and nanometer scales under different types of microscopes, she can see how they were made as well as their shape, size, and how the minerals and microbes in each sample are arranged.
But as her dissertation project on the bacteria from the mine progressed, her research took a turn. A colleague showed Chan similar bacteria that grow on an underwater volcano just off Hawaii’s Big Island. Like the mine, volcanoes have high concentrations of heavy metals seeping through the earth’s crust and into the water.
Chan studied the microbes under the microscope and realized she was onto something.
“It was amazing because (these bacteria) looked very similar to the ones I was finding in the mine,” she said. “I thought, my gosh, there must be some similarities between these two bacteria but they’re completely different because one is living in a mine in Wisconsin and other on a volcano in Hawaii.”
She thought there could be value in comparing what she learned on land to the deep ocean. Her interest led her to apply for and receive a National Science Foundation Ridge 2000 Fellowship. The award, which is part of a program that brings researchers together to study ridges in the deep ocean, supported her post-doctorate research at the Woods Hole Oceanographic Institution (WHOI). There, she learned the tricks of the ocean science trade and participated in research cruises to get samples of the bacteria using a remotely operated vehicle (ROV).
“There are mat fields that we believe are thousands of square meters in extent,” she said, comparing the ocean bacteria to the relatively smaller mats of mine bacteria. “It’s orange everywhere.”
In addition to studying how the bacteria affect the chemistry of their environment, she is working to understand biogeochemical cycling in the past. The bacteria are part of the environment’s iron and carbon cycles, and she looks at fossilized bacteria to learn more about their history.
“The microbes use the energy they get from iron oxidation to fuel carbon fixation and thus could be a significant carbon sink. This means they use chemical energy instead of light to accumulate and store carbon,” Chan explained.
Chan said she plans to continue land-based studies in addition to ocean work at the University of Delaware because the two complement each other so well. She said she’s excited about the collaborative community at UD as well as the top-notch facilities.
Chan will set up research labs in both Geological Sciences’ Penny Hall and the Delaware Biotechnology Institute, where she will take advantage of a new cryo-electron microscope in the Bio-imaging Center.
To UD she’ll bring years of training as a scientist. She earned her master’s degree in civil and environmental engineering and bachelor’s degree in geological and environmental sciences from Stanford University. She also has experience working as a consultant on bioremediation projects.
Growing up in Baton Rouge, La., with a physicist father and a geochemist mother, science has always been a part of her life. Her brother became a chemist and she chose geomicrobiology.
“We often talk about scientific topics and scientific life at the dinner table,” she said. “It’s all in the family.”
For more about the College of Marine and Earth Studies, visit www.ocean.udel.edu.