Superfund Research Program

December 2022

Hot Publication

In a recent study, researchers at the University of Iowa found that polychlorinated biphenyl (PCB)-degrading microorganisms can reduce PCBs emitted from contaminated sediment into the air. PCBs are widespread environmental pollutants and evidence has shown that exposure to PCBs increases the risk of developing adverse health effects, such as poor birth outcomes, cardiovascular disease, hypertension, and diabetes.

In this study, researchers hypothesized that PCB emissions from contaminated sediment could be minimized by adding microorganisms that naturally degrade PCBs, a process called bioaugmentation. They tested this in lab-scale bioreactors — devices that support microbial growth in controlled microenvironments — using PCBs from contaminated sediments and Paraburkholderia xenovorans strain LB400, a type of bacteria which was isolated from PCB-contaminated landfill soil in 1985.

To test whether the microorganisms could minimize emissions from sediment to air, they measured the concentration of PCBs in the sediment and air in bioreactors with PCB-degrading microorganisms added and in those without over 35 days. The results showed that bioaugmented treatments decreased total PCB mass in the vapor phase by an average of 57% in comparison to non-bioaugmented controls. The microorganisms preferentially degraded PCBs with lower numbers of chlorine atoms, which are more likely to volatize from soil than other PCBs.

They also tested the effect of saponin, a compound found in plants that may make PCBs more bioavailable for microorganisms. They found that saponin allowed for a stable abundance of a gene responsible for PCB degradation. This suggests that saponin could aid in biodegradation, the authors noted.

According to the researchers, their results show that PCB-degrading microorganisms can lower PCB emissions from contaminated sediments, potentially reducing human exposure.

To learn more, please refer to the following sources:

  • Bako CM, Martinez A, Ewald JM, Hua J, Ramotowski DJ, Dong Q, Schnoor JL, Mattes TE. 2022. Aerobic bioaugmentation to decrease polychlorinated biphenyl (PCB) emissions from contaminated sediments to air. Environ Sci Technol 56(20):14338-14349. doi:10.1021/acs.est.2c01043 PMID:36178372 PMCID:PMC9583607