From the Seafloor to Outer Space: Marine Microbiology in the Girguis Lab

The ocean floor may be the most treacherous place on Earth. It’s highly acidic, 350 degrees Celsius, and has an atmospheric pressure of around 250 times what humans normally experience. Walking through Harvard Yard, most students don’t realize these conditions are just steps away — in Peter R. Girguis’s lab.

Girguis, a professor of Organismic and Evolutionary Biology at Harvard, specializes in biochemistry and ecological physiology. His work focuses on the deep sea, studying the “linkages” between marine organisms and their environment, with implications for everything from space exploration to human health.

His lab’s research also ties into a broader, fundamental question about how organisms withstand intense ecosystems. In working to answer this, Girguis has even collaborated with space researchers at NASA aiming to identify potentially habitable environments in our solar system.

“NASA turns to folks like me who study life in extreme environments,” Girguis said. “But we also build tools to go underwater, which NASA does not do.”

Girguis shares a birthplace with the Apollo space program — Downey, California — where his mother worked in aerospace engineering. He said he once considered becoming an astronaut or a pilot, but without the “aptitude” for either path, he started college as a pre-med student until one fateful oceanography class.

“When I took oceanography, I realized, ‘Wow, this planet has got this giant ocean, and sometimes we act like it doesn’t exist,’” Girguis said.

Working with Worms

Since his first classroom exposure to the ocean, Girguis has built a career studying microbes and their role in aiding the survival of deep-sea organisms — primarily, species of six-foot tubeworms on the ocean floor.

“There are two worms that I’ve done a lot of work on for 25 years now, that are two meters long, and they are really muscular, robust animals,” he said.

Girguis has spent more than two decades researching the symbiotic partnerships that worms form with bacteria in order to thrive under high-pressure, high-temperature conditions in one of Earth’s most challenging environments: deep-sea vents.

“The water coming out of a vent can be 350 degrees Celsius, and it is acidic enough to dissolve a lot of metals,” he said, adding that the worms are surrounded by chemical compounds coming out of the vents that are “more toxic than cyanide.”

How do the worms withstand these conditions? Girguis said his lab identified the “secret sauce to living at a vent” — the worms’ advantageous symbiotic partnerships with bacteria.

“They culture deep inside their body between 10 and 100 billion microbes, and they feed those microbes chemicals,” he said. “It sucks up that hydrogen sulfide, that toxic stuff, takes it to the microbes.”

The microbes aid in a process called chemosynthesis — an alternative to photosynthesis that organisms use to generate energy in the absence of sunlight.

“The microbes, in turn, harness energy from a chemical reaction, and they convert CO₂ into sugars the way a plant does — but they do this in total darkness, and they do this at astonishing rates,” he added. “And so these worms grow faster than bamboo, kelp, and wheat — all these fast-growing things.”

Girguis’ Gadgets

To support his research, Girguis has used his expertise in engineering to build an array of research tools tailored to the demands of his work.

One is a mobile research lab, which he calls “our version of the International Space Station.” This one-room research lab can be loaded onto ships and chemically transforms seawater into hydrothermal vent water, which keeps samples alive on board.

“We change the pH, we change the chemistry — we alter it completely,” Girguis said.

The mobile labs use pumps to transport water into titanium high-pressure vessels, where deep-sea organisms can survive “because they think they’re at a hydrothermal vent,” according to Girguis.

Another piece of technology Girguis devised is a gas mass spectrometer, which “sniffs” out key biological gases — oxygen, sulfide, carbon dioxide — with its wand-like sensor.

Girguis built the spectrometer to overcome the limitations of traditional sampling methods, which he said were both costly and inefficient.

“For years, we would go down with a high-pressure titanium syringe, suck up some water, close it, and bring it up, and that titanium syringe would get us one sample — and cost $20,000 to build,” Girguis said.

That’s when the idea hit him.

“When I started here at Harvard — and a little bit before — I said, ‘Well, why don’t we just build an instrument that we put it in a one-atmosphere housing, and go down and sniff it?’”

The impact of Girguis’ gadgets stretches beyond the lab to other scientists across the country. Stanford Assistant Professor Anne E. Dekas ’04 said Girguis’ work has strongly impacted her own, adding that she has “always felt that Pete was available to help” — even just as a favor.

“Pete has developed some really interesting technology to do that,” Dekas said, referring to Girguis’ deep-sea sample collection tools. “He was so open to lending it to us, even though, again, he’s not even a funded collaborator on that project.”

Girguis’ innovative methods seep into his approach to advising. Isabel R. Baker, a postdoctoral fellow at Johns Hopkins and former Ph.D. student in the Girguis Lab, described Girguis as a creative advisor, pointing to his “tinkering” and ability to “fashion things in a matter of an hour.”

As a member of the Girguis Lab, Baker went out to sea to do research on her own, which she says is “very unique” to do early in one’s PhD. According to Girguis, on average, a representative of the Girguis Lab and Girguis together spend about two out of every twelve months at sea.

Launching to Space

Professor Scott V. Edwards ’86, a colleague of Girguis in the OEB department, said research from the Girguis lab has relevance to “everything from ecological interactions to genomics.” This expanded horizon of application has given the Girguis lab collaborative opportunities with NASA, helping to design robot technology.

“Professor Girguis’s work already, and his more recent work in collaboration with NASA has made a tremendous impact in NASA’s planning for, ‘What would a rover or a robot look like on an icy ocean world, searching for life?’” Baker said.

According to Christopher R. German, a collaborator with Girguis and professor at the Woods Hole Oceanographic Institute, the team is “just wrapping up” one particular collaboration with NASA launched in 2020.

“That project has been focused on taking what we know about Earth’s deep oceans — and specifically, how life extracts energy from geochemical reactions at the deep seafloor: a strong suit for the Girguis Lab,” German wrote in a statement.

Other applications for the lab’s research include climate change and the natural regulation of methane in earth systems. One area of Girguis’ work examines how the ocean processes methane in the ocean, which connects to the worldwide cycling of greenhouse gases like carbon dioxide.

Dekas said Girguis’s work is an example of research that grapples with the increasing threat of greenhouse gas emissions “in the most accurate and thoughtful way.”

But beyond climate change, Dekas said Girguis’ work has clear potential to inspire a new generation of oceanographers.

“His work also just raises public excitement about the beautiful diversity of life on this planet,” Dekas said. “That kind of enthusiasm for science can help bring people into STEM fields, no matter where they start.”

Girguis said his work is a reminder of the strong human connection to the natural world.

“It’s easy to think of we humans as being separate from nature,” he said.

“It’s like the undiscovered country, right? This place that we know so little about,” Girguis added. “At the same time, I think that we are clearly and deeply connected to what happens in the ocean.”

— Staff writer Neeraja S. Kumar can be reached at neeraja.kumar@thecrimson.com.
—Staff writer Mana Tsuruta can be reached at mana.tsuruta@thecrimson.com. Follow her on X @ManaTsuruta.