Environmental Cleanup of Harmful PCBs Using Bacteria

 By: Raul Gonzalez

Polychlorinated biphenyls (PCBs) are man-made chemicals found in the soil environment of industrial job sites and cause human health risks like cancer and heart disease.  Low chlorinated PCBs easily move freely into the air to be inhaled by humans.  This experiment used a bacteria, LB400, to see if it was capable of cleaning up PCBs in the soil—this is called bioremediation.  The experiment used flasks filled with  wet soil and sponge filters on the neck and bottom to see how many PCBs were found in air and water.  The experiment also investigated using saponin, a chemical defense mechanism found in plants.  Four bottles were studied: soil only, soil plus saponin, soil with LB400, soil with LB400 plus saponin.  Results showed a 77% decrease of low chlorinated PCBs in the group with LB400, confirming biodegradation.  Surprisingly, a 92% decrease in the LB400 plus saponin confirms what is called bioaugmentation—the addition of something to a bacterial culture.  The next step is to couple this technique using biofilms on activated carbon for a one-size-fits-all method of large-scale delivery.  This technique is a proven effective method for reducing the amount of PCBs inhaled in communities affected by these type of pollutants. 

 

 Figure 1 - Graphs A, B and C show the amount of PCBs in the air.  The green circles included the LB400 bacteria plus saponin which shows the lowest emissions detected.  Graphs D, E and F show the PCB found in the water.  Figure taken from Bako et al. 2022. 

Reference

Bako, C. M., Martinez, A., Ewald, J. M., Hua, J. B., Ramotowski, D. J., Dong, Q., Schnoor, J. L., & Mattes, T. E. (2022). Aerobic bioaugmentation to decrease polychlorinated biphenyl (PCB) emissions from contaminated sediments to air. Environmental Science & Technology, 56(20), 14338–14349. https://doi.org/10.1021/acs.est.2c01043