PCB bioremediation potential of thermophilic strains from shallow hydrothermal vent (Vulcano Island)

Due to their environmental features, marine hydrothermal systems could be interested by the production of several reduced compounds, i.e. low molecular weight hydrocarbons, long-chain alkanes and polycyclic aromatic hydrocarbons, and act a selective pressure for the establishment of specific and resistant microbial communities, well adapted to such extreme conditions. This condition could be useful for the isolation of bacteria with peculiar abilities, suitable for biotechnological applications. Currently, little is known about degradation capacity of culturable hydrocarbon-degrading bacteria from marine hydrothermal vents.In this study, sediment samples collected at the hydrothermal vent system of Levante Bay (Vulcano Island) were used as source of isolation of hydrocarbon degrading bacteria. On a total of 52 isolates, cross-growth tests on different hydrocarbons were carried out. In addition, the oxidation of polychlorinated biphenyls was evaluated by growing isolates in the presence of the Aroclor 1242 as the sole carbon source, and by searching for the catabolic gene bphA in all strains. Among the total of isolates selected as positive from the degradation tests and growth in the presence of biphenyl (49), 19 bacterial strains harbored the bphA gene. The strains were selected for a biodegradation experiment, which showed promising potential in the bioremediation field. The results obtained highlighted the occurrence of hydrocarbons and polychlorinated biphenyl in the investigated area, and provides new insights into the biotechnological potential of culturable oil-degrading bacteria from shallow-sea hydrothermal regions. It confirms the potential of such marine hydrothermal sites as optimal source for isolation of thermophilic degradative strains, to be proposed in the cleanup strategies of contaminated marine area.