Crab-Shaped Robot Lends a Claw

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Fellow unites bacteria with a robot to remove toxic PCBs from the environment

17-crab-shaped_photo1_fvStudying biological systems engineering at Virginia Tech, MJ Rice watched her peers hack bacterial DNA to make the surface of their cells display certain proteins. This inspired her to take advantage of the technology herself.

She’d recently learned about toxic chemicals called polychlorinated biphenyls, or PCBs. PCBs were used in many products, like electrical equipment and plastics, until they were banned in 1979 for their adverse health effects in animals, including humans. But PCBs are hardy contaminants, and remnant PCBs still threaten the safety of seafood and health of marine ecosystems in Chesapeake Bay today.

“Stopping contaminants at the source is not enough because there are some, like polychlorinated biphenyls, that don’t break down naturally and require active removal,” Rice says. “These are the contaminants that interest me the most.”

As a Virginia Sea Grant graduate research fellow, Rice is using bacteria to grab PCBs from the Bay. She’s already figured out how to alter bacterial DNA in a way that makes the surface of their cells display proteins that bind to PCBs, but realized her bacteria need a vessel.

"Stopping contaminants at the source is not enough."

“And as engineers, our first thought is Robot,” she says.

Since PCBs settle on the water’s bottom, she designed a robot that mimics an iconic Chesapeake Bay species: the blue crab. She envisions her robot scuttling along the seafloor, collecting water samples that pass through a chamber containing PCB-binding bacteria. After the bacteria have snatched all the PCBs from a sample, the water will be flushed back outside and the robot will take in another, cleaning the Bay one sample at a time.

Rice named the system “Crustacean Replicate Automated Benthic Bioremediation Ocean Technology,” a mouthful justified by its acronym: CRABBOT.

“I’d really like to be able to put this CRABBOT in the water,” says Rice, eager to exercise her scuba certification. “I want to dive and see it in the field, not just a tank.”

Rice’s love of science, math, and building encouraged her to become an engineer, but growing up just outside of Baltimore, Maryland, she is “naturally drawn to marine work and Chesapeake Bay,” and had “been thinking about how to tailor projects toward benefitting the environment.” She is currently a master’s student in biological systems engineering at Virginia Tech, and earned her bachelor’s degree in the same subject in 2015.

By Chris Patrick, science writer
"As engineers, our first thought is Robot."