Selection and characterization of indigenous hydrocarbon-degrading bacteria from tourist ports in the Mediterranean Sea Basin

Pollution by petroleum hydrocarbons is one of the major environmental problems in ports and it is mainly associated with ship/boat traffic and related facilities. Ports are not closed systems and their pollution may impact adjacent coastal areas. Hydrocarbon degraders and particularly the obligate hydrocarbonoclastic bacteria carry out a fundamental and global activity in biological removal of hydrocarbons in marine habitats. This studywas carried out withinMAPMED, amultidisciplinary project aimed to improve the environmental sustainability of tourist ports in the Mediterranean Sea with regard to monitoring and reduction of hydrocarbon pollution. Three tourist ports were selected as case study sites: Cagliari (Italy), El Kantaoui (Tunisia), and Heraklion (Greece). The degradation potential of the autochthonous bacterial communities was evaluated enumerating heterotrophs and hydrocarbon degraders by MPN in the surface seawater. Heterotrophs were significantly more abundant in seawater from Cagliari port as compared to El Kantaoui and Heraklion ports. On the contrary, higher viable titles of dieseland phenanthrene-degraders were found in seawater from El Kantaoui port compared to the other two areas. Hydrocarbon-degrading bacteria were isolated and characterized regarding their phylogenetic position and catabolic abilities. The hydrocarbon degradation activities were evaluated by GC-MS in aerobic batch reactors on diesel as carbon source. The majority of degraders from Cagliari were assigned to Pseudomonas whereas strains from El Kantaoui and Heraklion were assigned to Alcanivorax and Marinobacter. The selection of the most appropriate methodologies for the eco-efficient remediation of petroleum-hydrocarbon contamination of selected sites is currently in progress.