PCB-oxidizing bacteria in Arctic and Antarctic lakes: insights into bioremediation potential in polar ecosystems

Polychlorinated biphenyls (PCBs) are long-lasting organic pollutants commonly found in polar regions due to their ability to be transported and deposited over long distances in the atmosphere. This study examined the levels of PCB contamination in water and sediment samples taken from Arctic lakes (Ny-Ålesund, Svalbard) and Antarctic lakes (Livingston Island and Deception Island) and evaluated the biodegradation capabilities of local cold-adapted bacteria. Our analyses highlighted that Antarctic lakes had higher PCB concentrations than Arctic lakes, and the sediments acted as sinks for these pollutants. Variability between lakes was also observed, with Deception Island exhibiting higher PCB levels, which may be attributed to local environmental and volcanic influences. Several bacterial strains able to grow with PCBs as the sole carbon and energy source were isolated and identified from sediment samples, primarily belonging to the genus Pseudomonas. Arctic isolates exhibited higher biodegradation efficiency, particularly those possessing the bphA gene, which plays a key role in the initial steps of PCB degradation. These preliminary results underscore the essential role of polar lakes as both reservoirs and key areas for PCB degradation, while also highlighting the potential of cold-adapted bacteria for bioremediation in extreme environments.