When Kate Fullerton joined a lab back in 2017 as a graduate student at the University of Tennessee her professor, microbiologist Karen Lloyd, gave her an unusual choice. Siberia or Costa Rica?
“I didn’t want to go anywhere that it was cold,” Fullerton said. She took the Costa Rican project but there was a catch. “It was like, OK, take the project. We leave in a month.”
Fullerton who was 23 at the time and barely finished with her first year of graduate school, had to plan and prepare for an international research project that would eventually involve scaling to the top of a volcano with an injured ankle.
It worked out. Her thesis would end up being published in Nature, one most prestigious scientific journals in the world.
“It was a little bit of a trial by fire,” said Fullerton with a bit of a smile. “But I succeeded.”
Now, four years later and 27, she’s applying that world-class knowledge back in Knoxville as a Pellissippi State Community College instructor.
Finding life in surprising places
Scientists have discovered life almost everywhere they’ve looked on Earth, even in the most unexpected places like the deepest, coldest parts of the ocean and boiling, acidic lakes.
Fullerton was part of an international research team that discovered bacteria living inside volcanic hot springs deep underground. But the bacteria weren’t just living in a harsh, strange place. They were actually helping trap carbon dioxide, a climate change culprit.
That’s important because we don’t really understand what happens to carbon when it is forced inside the earth’s crust by the movement of continental plates. Volcanoes are hotspots of carbon emissions, so high volcanic activity can mean warmer global climate overall.
“Part of the reason it (subsurface life) remained a black box for so long is because how the heck do we even sample this?” said Fullerton. She said that typically scientists need to drill hundreds of meters underground or rely on access to abandoned mines. Costa Rica’s hot springs are a peephole into a world we cannot visit.
“There’s little cracks where you have a little bit coming out here and a little bit there,” said Fullerton. “So we basically hunted across the country trying to find these little sources.”
Fullerton’s passion for science is obvious when you talk to her. She laughs about getting her research materials through customs and breezily explains her work with apt visual metaphors.
Pellissippi State Community College get to benefit from that. She fell in love with teaching while working at UT.
“I would have students come knocking at my door asking for help,” said Fullerton. “It’s just what I want to do.” .
Life beneath our feet
Fullerton’s study straddles two scientific worlds: Biological processes and long-term geological forces.
Frederick Colwell, a microbiologist at Oregon State University, explained that this study reveals processes that are important for understanding how carbon, climate and life interact. Colwell was not involved with the study but he has worked on microbial life in deep-sea hydrothermal vents and deep under the sea floor.
“We need to understand the carbon cycle as it naturally happens on our planet better than we do,” Colwell said. “The subsurface of our planet hosts a very large amount of biomass, and not too many decades ago we were pretty ignorant of any of that.”
In their lightless homes, deep crust bacteria cannot rely on the sun for food. Instead they feed on carbon molecules dissolved under high heat and pressure. These bacteria could block up to 20% of the carbon dissolved in hot springs water, preventing it from re-entering surface soils or the atmosphere.
Lloyd, the UT microbiologist, told Knox News that studies like this could help us better capture, and sequester, dangerous carbon.
“What we found is that there are a lot of them and they do a lot of this (carbon sequestration),” Lloyd said. She explained that other deep bacterial communities in less volcanically active areas did not appear to be as good at holding carbon in the crust. “We found ten times more carbon locked up than in some of those other ecosystems.”
Solid rock isn’t so solid
The bedrock under our feet in Tennessee is not a solid block. It is riven with cracks, fissures and caves. Layers of stone and clay are laid and folded over each other over the eons.
Water carves holes, too. In our part of the world, thousands of limestone caves make any cross section of the ground look like a slice of layer cake.
In places like Costa Rica, plate tectonics add another element because of pressure and heat from below. The hard crust of the earth is broken up into large chunks called tectonic plates that float on the mantel, a liquid layer of molten rock.
These plates are slowly moving, driven by currents of heat from deeper in the earth. Where plates slide into each other, or away from each other, you get volcanoes.
As the wet, dense oceanic crust sinks into the earth it gets hotter, releasing molten rock and superheated water. The water and molten rock rise together, forming chains of volcanoes. Most of Costa Rica grows out of a spine of volcanic mountains.
Doing the work
Scientists had suspected that life might exist in this extreme environment but it hadn’t been extensively surveyed. Fullerton’s study was the first to try it.
Costa Rica is an unusually good place to sample because it’s rich with volcanic springs. They emerge as small ponds on cattle ranches or warm seeps from hillsides. They even pop up as puddles on rural Costa Rican roads.
“I think more people are going to be doing this in the future but it’s not yet being done, using springs as a way to access a large landscape-scale of subsurface life,” Lloyd said.
“You have to respect volcanoes,” the New Jersey native mused.
The team drew water and filtered out bacterial samples, freezing them in a giant, liquid-nitrogen cooled thermos carried on the back of a pickup truck. Once they got back to Tennessee, Fullerton extracted bacterial DNA so the team could identify the species and then analyzed the data.
“It was a wild project and I consider myself very lucky to have been involved with it,” said Fullerton.
The team was brought together by the Deep Carbon Observatory, a global scientific initiative combining biology, physics, chemistry and geology to study processes happening deep inside the earth.
“The point (of the observatory) was to get those different disciplines talking with each other to answer the enormous question of how does carbon really move inside earth,” said Lloyd, “Something like 99% of all carbon on Earth is actually inside it.”
From Costa Rica to Community College
Fullerton now works as an instructional systems specialist at Pellissippi State, where she creates virtual science lessons. Fullerton says that while she loved doing research, her new passion is teaching.
At first glance it might not seem like the most natural move but Fullerton doesn’t see it that way. To do her research, Fullerton taught herself to code, build databases, do statistics and — most importantly — troubleshoot. All of those skills came into play in designing online learning courses. It was an interesting challenge to try to present hands-on activities in a digital space.
But more importantly, Fullerton said working at Pellissippi allows her to share her passion for science with her students, many of whom are adult learners.
“There’s a lot of potential for me to be able to do some real good and have a large impact on a large number of students,” she said.
“Economically, they’re an underserved population. They didn’t always have the opportunities to explore these interests. As instructors, this is our opportunity to make it a worthwhile experience.”
Fullerton hasn’t decided whether she wants to continue to get her doctorate or devote herself to teaching. She and the rest of the team are still working with the data they gathered from Costa Rica and anticipate publishing another study soon. For now, Fullerton is happy right were she’s at.
“I really love Pellissippi now,” she said with a smile. “Maybe I’ll just slowly weasel my way up the administrative ladder. Maybe that’s where I’ll go. Who knows?”