Genotyping of Alcanivorax spp. strains isolated from the Mediterranean Sea shows evidence of geographic divergence

The Mediterranean Sea is an environment at high risk of pollution due to its physical characteristic, high urbanization and the impact of oil extraction, refining and shipping activities. The Mediterranean Sea hosts several polluted environmental niches, hence it can be a good source of microorganisms with new degradation capability to be exploited for bioremediation technologies. Aim of the work was the genotyping of a collection of hydrocarbonoclastic bacterial isolates of the Alcanivorax genus, in order to identify different genotypes within the same species and/or the isolation site. The collection comprised 179 isolates belonging to 4 Alcanivorax species (A. borkumensis, A. dieselolei, A. jadensisand, A. venustensis) isolated from 9 stations located across the Mediterranean Sea. The bacterial isolates were analyzed using two different molecular fingerprinting techniques - Internal Transcribed Spacer (ITS)-PCR and BOX-PCR - identifying 85 genotypes. The combination of the two techniques indicated A. jadensis as the more heterogeneous specie, showing 60 different genotypes out of 88 isolates, while A. borkumensis was the less diverse specie, with only 17 genotypes out of 75 isolates. Furthermore, the study highlighted that all the strains belonging to the same genotypic group were isolated from the same station and were absents from the others, even when the stations were located in the same geographic area. This finding supports the existence of geographic divergence within the Alcanivorax genus, highlighting the invaluable potential of the Mediterranean Sea as a source of novel microorganisms in the perspective of bioremediation processes.