PCB-degrading bacteria from the Arctic Kongsfjorden (Svalbard Islands)

Polychlorinated biphenyls (PCBs) were produced between 1929 and late 1970s and used in several industrial applications. They show bioaccumulation and biomagnification behaviours, so they pose a serious risk to the environment. Eight strains (i.e.. Pseudomonas sp. CIW-9, Devosia sp. DS-1, Algoriphagus sp. EW-10A, Bizionia sp. BS-8B, Microbacterium sp. C3W-24A, Salinibacterium spp. C3W-3 and ES-1, and Leifsonia sp. C1S-22B) isolated from the Kongsfjorden, and previously tested for the presence of the bphA gene, were selected to test their degradation efficiency in presence of Aroclor 1242 at 15 and 4 °C. The composition and concentration of PCBs were determined by high resolution gas chromatography-mass spectrometry (GC-MS). Results showed that isolates were able to reduce between 3.5-60.1% of the PCB mixture. None of the congeners was totally removed. Tested strains had generally greater degradation efficiency at 15 than at 4°C, exception for strain C1W-9 that showed the maximum degradation efficiency at 4°C (37.1%). Conversely, strain DS-1 showed better ability to use (up to 60.1%) Aroclor 1242 at 15°C. Results clearly indicate that the biodegradative potential was not strongly related to the phylogenetic affiliation of the analyzed isolates. Furthermore, the outstanding degradation abilities exhibited by our isolates at 4 °C, close to the in situ seawater temperature, reveal that the indigenous microbial community has a catabolic potential for PCB aerobic degradation that could occur at in situ environmental conditions.