About This Project

PCB is an organic chlorine compound that bioaccumulates and persists in the environment. Production has been banned in the US, but ecosystems are still facing repercussions from decades ago. Team iTesla-SoundBio aims to combat this by transferring genes responsible for producing PCB-dechlorinating enzymes from the anaerobic Dehalococcoides mccartyi bacterium, in which they’re naturally found, into an aerobic, easier-to-work-with bacterium, such as E. coli.

Ask the Scientists

What is the context of this research?

Polychlorinated biphenyls (PCBs) are a class of man-made chemicals that contaminate many lakes and waterways. PCBs were produced for industrial and commercial applications. Although their manufacture has been banned or severely restricted, they still remain in the environment today, mainly from the disposal of old electrical equipment. Even though they persist because they are highly nonreactive and resistant to acids, bases and heat, it has been known for several decades that PCBs slowly break down in the environment. The pathway by which they are broken down was only recently discovered. A bacterium called Dehalococcoides mccartyi breaks down PCBs with a variety of enzymes, the genes for 3 of which (pcbA1, pcbA4, and pcbA5) were sequenced in 2014 by Wang.

What is the significance of this project?

PCBs are probable human carcinogens, have acute toxic effects, and cause immune system and thyroid effects. They are also known to disrupt hormone functions and have developmental effects - woman exposed to PCBs can give birth to children with significant neurological and motor control problems. Compared to other waterways, the Puget Sound has a considerably high level of PCBs, which bioaccumulate in organisms. In particular, the biomagnification of PCBs up the food chain has been severely detrimental to orcas. The bacterium Dehalococcoides mccartyi can break them down, but it is anaerobic and only obtain energy through organohalide respiration, and thus difficult to work with.

What are the goals of the project?

We plan on transferring pcbA1, pcbA4, and pcbA5 - the genes responsible for producing the PCB-dechlorinating enzymes - into E. coli or other microorganisms, as this may be very beneficial for potential PCB cleanup operations. The end goal is the development of a process using the produced enzymes to facilitate PCB cleanup or the production of technology containing the genetic pathway that could be used to clean up PCB-contaminated environments. During this, we hope to reach out to local students and the community to teach them about the importance of genetic engineering, synthetic biology, and their applications in our daily lives, as well as how they can get involved and start on their way to becoming a genetic engineer.