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It's the little things that matter

Mary Ann Moran studies bacteria with a global impact

by Sam Fahmy (BS '97)

Standing on the bank of a salt marsh on Georgia’s Sapelo Island wearing shin-high rubber boots, Mary Ann Moran (PhD ’87) encourages a group of high-school students to join her.

“Just go ahead and get muddy,” the UGA professor of marine sciences says. “It’s fun.”

The goal is to collect brackish water that the students will later analyze using state-of-the-art DNA techniques. Marine bacteria are still so poorly understood that there’s a good chance that many of the students will identify new species. “About half will find bacteria that have never been found before,” Moran says.

For the past decade, Moran’s research has focused on a particular group of marine bacteria known as roseobacters for the pink color of some of the cells. Moran’s work, recently awarded a $2.6 million grant from the prestigious Gordon and Betty Moore Foundation, is illuminating how these marine bacteria move sulfur from the oceans to the atmosphere, where it plays a role in seeding clouds and regulating the Earth’s climate.

Her trip to Sapelo with the high school students, a group of 20 in an advanced placement class at Cedar Shoals High School, helps bring new scientists to a field that Moran says is important but often overlooked. Even those who go on to become chemists, musicians, accountants or doctors will have a sense of the vital role bacteria play in the health of the planet.

“I think it’s very important for people to understand how the Earth works and how the single-celled organisms that can’t be seen and sometimes smell bad are in many ways actually making the Earth run,” Moran says.

Budding scientists

Ever since she was a child, Moran has been fascinated by nature. She spent much of her spare time in the backyard, gardening or feeding birds.

“And this was Long Island,” she says. “Not really nature central. But I was always outside and I just like seeing how many small things fit together to make a more complete system.”

Now her work brings her to Sapelo Island, population 70, give or take a few. The 10-mile-long, two-mile-wide barrier island is home to the UGA Marine Institute. At Sapelo, wide live oaks draped in Spanish moss dominate the landscape and white-sand beaches taper into the Atlantic. Salt marshes stretch for miles toward the mainland as a sea of Spartina grass harboring birds, fish, crab, shrimp and—of course—billions of bacteria.

For about 20 years now, Moran has been making the five-hour drive from Athens to catch the ferry to Sapelo. Most of the time, she comes alone or with her research group.

This time, Moran and the Cedar Shoals students will spend two days at the UGA Marine Institute studying the diversity of the wildlife at Sapelo—everything from the fishes to the unseen bacteria.

Stella Guerrero, the students’ biology teacher, says that working with Moran gives students hands-on experience in science and lets them know that a career in science is a viable, rewarding option.

“Scientists like Mary Ann are very into what they’re studying,” Guerrero says. “And they transmit that energy to the students.”

Roseobacters’ role

After arriving on the island and feasting on a dinner of low country boil and fried chicken at Lulu’s Kitchen—the island’s only restaurant—the students head to the Marine Institute.

There, they begin honing the basic skills that will help them explore the microbial world. They gather around Moran as she distributes petri dishes, also called plates.

“Make sure the plates don’t stay open,” Moran says, explaining that they don’t want to contaminate the medium in which they’ll grow their bacteria.

The techniques she’s teaching the students are the same ones she uses with striking results in her lab.

About a decade ago—and using a recipe that she borrowed from emeritus UGA professor Larry Pomeroy—she was able to grow a group of bacteria known as marine roseobacters in her lab. Very little was known about this group of bacteria, but their sheer abundance piqued Moran’s interest.

“We reasoned that if they’re so abundant, they’ve got to be doing something important,” Moran recalls.

And they were right. One of Moran’s post doctoral students, Jose Gonzalez, now at the University of La Laguna in Spain, discovered that roseobacters play a role in taking sulfur from the ocean and moving it into the atmosphere.

A few years later, Moran’s team discovered that the bacteria can also take sulfur and—instead of sending it into the atmosphere—turn it into a form that’s important in the ocean’s food web.

“They were the only bacterium isolated at that point that had both capabilities,” Moran says.

And just this year, one of Moran’s doctoral students, Erinn Howard, in collaboration with the lab of microbiology professor William Whitman, discovered the gene that allows roseobacters to keep sulfur in the ocean rather than releasing it into the atmosphere.

Now, researchers can look for other bacteria that have this gene and can explore how such bacteria are distributed in the oceans and the factors that influence how they direct marine sulfur.

Atmospheric sulfur seeds clouds, and clouds influence global climate by determining how much light gets to the Earth or is reflected back to space. Since the sulfur-containing compound handled by the roseobacter cells is the major, non-human input of sulfur into the atmosphere, understanding the factors that influence which way the bacteria route sulfur helps atmospheric scientists more accurately model the effects of global warming.

“Ultimately, we would really like to be able to both know how much sulfur gets into the atmosphere and understand what processes in the ocean control that amount,” Moran says. “Our work with marine bacteria is admittedly many steps away from that, but that’s the goal.”

Field science

Back on Sapelo, the first order of business is to collect water samples for the students’ bacterial studies. After a bit of cajoling, the students follow Moran down to the marsh, where they measure the water’s salt concentration and temperature.

A bit of water flows over the top of Moran’s boots and creeps up her jeans, but she honestly doesn’t mind. She simply pours the water out of her boots when she’s done. “That’s field science, anyway,” she says with a smile.

Bacteria are so abundant in seawater—there are about 100,000 in a single drop—that the students must return to the Marine Institute to dilute the samples before placing them on plates containing a growth medium. The plates are then carefully sealed and packed for their trip back to Athens.

With the microbial part of their field work complete, the students hop aboard the Marine Institute’s research vessel, the RV/Spartina, as it trolls the estuary and pulls in fish, shrimp, crabs, sea squirts and other aquatic creatures that the students dutifully catalog.

After the cruise, the students grab a quick lunch before heading to the beach to identify shells. Then they head home, taking with them cardboard boxes that contain the bacteria they’ll later identify using the same DNA techniques that Moran uses in her lab.

New discoveries

After giving the bacteria a few weeks to grow on the plates, Moran visits the students in their classroom at Cedar Shoals to teach them how to isolate the bacteria. A few weeks later, the students visit her lab to amplify—or copy many times—one gene in the bacterial DNA that serves as a “fingerprint” that helps them discover its identity. Later, they obtain the exact order, or sequence, of the base pairs that make up this gene.

Comparing the sequence they find with the sequences in a national DNA database, the students discover that many of them have indeed found species never before described.

“I never knew that there were so many species that were unknown,” says senior Mahul Amin.

Bob Hodson, who fondly recalls mentoring Moran when she was a doctoral student at UGA, says she’s motivated by an infectious enthusiasm about the natural world.

“Her strength is just an innate curiosity that only the best scientists, naturalists or, really, the best in any field have as their guiding force,” says Hodson, a former director of the UGA School of Marine Programs.

Moran’s work with young scientists, from high school students to post-graduate students, assures that future generations will keep asking important questions about the ocean’s unseen yet vital bacteria, Hodson says.

“They’ll carry her perspectives on science and on life in general with them wherever they go,” he says.

Cedar Shoals senior Sherrie Hall says that she didn’t know much about microbiology before the trip to Sapelo; afterward, she decided to spend the summer interning in Moran’s lab. “You get to find things that have never been discovered before,” Hall explains.

Moran’s curiosity, coupled with a knack for picking important questions, resulted in the award from the Moore Foundation, which funds projects that will improve the quality of life for future generations.

Moran was among a group of nationally known researchers selected for the grant, which offers the freedom to explore the field without being hindered by time-consuming grant applications.

“Really, as long as I’m conducting research in marine microbiology, the Moore Foundation is happy,” Moran says. “That’s the only stipulation as to how the money would be spent. And for a research scientist, that’s amazing.”

Sam Fahmy is a science writer in UGA's News Service.

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photos by Peter Frey (BFA '94)

Click on image to enlarge

UGA professor Mary Ann Moran (PhD '87)

Clara Smith prepares a water sample to study marine bacteria.

Yosheika Hubbard prepares a water sample to study marine bacteria.

Joseph Lester and Jeffrey Wang prepare a water sample to study marine bacteria.

Moran--handing a water sample to Joseph Lester--introduced a group of high school students to field science during an April trip to UGA's Marine Institute on Sapelo Island.

Yihe Dong examines a fish pulled from the trawling net during a trip aboard the RV/Spartina, the Marine Institute's research vessel.

(left to right) Geneva Edwards, Judy Bau, Allen Hayes and Marta Gaertig learn the same basic techniques Moran uses.

Hermit crabs were among the creatures found in the trawling net during the group's trip aboard the RV/Spartina.