PCB-oxydizing bacteria from the freshwater sponge Spongilla lacustris (Linnaeus, 1759) (Pasvik River, Arctic Norway)

The Pasvik River is one of the most important rivers in Northern Fennoscandia. Emission Lake Inari (Finland) marks the border between Norway and Russia and flows into the Barents Sea. This has significant anthropogenic impact due to the factories and the strong presence of mining activities on the Russian coast, which involve waste and waste emissions. In the framework of the multidisciplinary SpongePOP project (EU INTERACT - July 2014), this study aims at characterizing the bacterial community associated with the sponge Spongilla lacustris (Linnaeus, 1759), as well as in sediment next to the specimens, also in relation to the occurrence of polychlorinated biphenyls (PCBs). During a first survey, the concentration of PCBs (by gas-chromatographic analysis) and the structure of the bacterial community (by the Ion Torrent sequencing) were determined in both matrices. Obtained results showed a high concentration of PCB008 (2-4 'dichlorobiphenyl) in both matrices. Sediment and sponge samples were then enriched with biphenyl (BP; a PCB precursor) for subsequent bacterial isolation. A total of 72 strains (48 and 24 from sediment and sponges, respectively) were isolated from agar-enriched BP plates. Of these, 39 isolates (16 and 23 from sediment and sponges, respectively) were able to grow in the presence of Aroclor 1242, a mixture of PCBs. The amplification of the bphA gene, involved in the aerobic degradation of the PCB, confirmed the ability to degrade these pollutants in 39 isolates, mainly belonging to the Gammaproteobacteria and Actinobacteria.