The Cabo Rojo salt flats in the southwest region of Puerto Rico are part of a delicate ecosystem.
When most of us think of salt, it’s the sort in a cute shaker next to the pepper. But to microbiologist Dr. Lilliam Casillas, the salt-adjacent microbial mats she studies may contain medical breakthroughs that could save and improve millions of lives. From cancer therapies to new antibiotics to biopolymers that cement medical devices inside human bodies, Cabo Rojo is home to a microscopic world of gargantuan possibilities.
Found in the southwest region of Puerto Rico, Cabo Rojo is a mature salt flat that was first established by Puerto Rico’s indigenous Taíno people and later used by Spanish colonists as a commercial enterprise. Today Cabo Rojo is a stunning oceanfront wildlife refuge encompassing the salt flats that are still mined for the stuff you shake on your potatoes. While others visit for recreational or business purposes, Lilliam and her students come to gather samples for their research.
“We have to be very careful when we collect samples from Cabo Rojo,” says Lilliam. “This is an extremely fragile ecosystem that has taken decades to mature, so we need to tread lightly and take only what we need.”
Cyanobacteria isolated from a microbial mat sample collected by Lilliam and her team.
Lilliam instructs her students to enter the area gingerly, one soft footstep at a time. She likens the samples they collect to lasagna because of the three distinct layers found in the microbial mat. And, just as you would if helping yourself to a serving of the popular Italian casserole, they grab their portions using a regular kitchen spatula like the kind you have at home. They place the samples in Tupperware containers and exit via their own original footprints, like Danny Torrance escaping the snowy maze in The Shining.
Here is where the lasagna metaphor ends.
The samples they harvest have a gelatinous consistency with a top layer that is green, a middle layer that is pink and a bottom layer that is black. From the side, the chunk more closely resembles a Marc Rothko painting in 3D. And, after some time exposed to sunlight on the lab’s windowsills, the bacteria-rich slices issue an intense odor of rotten eggs. It’s an acquired smell.
“To me, the smell is wonderful,” chuckles Lilliam. “It means your bacteria are becoming less saline and more productive. This is when things start to become really interesting.”
Microbial mats like the ones Lilliam studies with her students are truly the bedrock of life on our planet. If humans someday needed to recreate a habitable organic environment in an alien setting, such microbe-rich samples would be among the initial building blocks. Fortunately, given its significance and fragility, Cabo Rojo was mostly spared from the ravages of Hurricanes Irma and Maria. But the University of Puerto Rico Humacao campus where Lilliam teaches and conducts research was not.
“The campus became a refuge for students and faculty because many of us were out of power for several months and didn’t have access to basic resources like drinking water and food,” says Lilliam. “Not having internet access was definitely a problem too. But for many weeks it was the absolute least of our concerns.”
The campus community worked together to clean classrooms and restore essential resources. Students expressed how the experience made them realize the value of family and community.
A stalwart champion for diversity in STEM, Lilliam has secured funding for a new program called PROUD, an acronym that means Puerto Rican Outstanding Diversified Program. As the first Latina in her family to obtain not just a college degree but a Ph.D., Lilliam is passionate about helping others overcome the obstacles she had to face alone. With the tireless efforts of Lilliam and other fierce champions like her working to create more opportunity in STEM for women and people of color, the field of microbiology is poised to become as multifaceted as Cabo Rojo’s glorious microbial mats.