Isolation of Gram positive n-alkane degraders from a hydrocarbon contaminated Mediterranean shoreline

Aims: To investigate the petroleum hydrocarbon (HC)-degrading potential of indigenous micro-organisms in a sandy Mediterranean coast, accidentally contaminated with petroleum-derived HCs. Methods and Results: Using culturable methods, a population of Gram-positive n-alkane degraders was detected in the contaminated soil. Five isolates, identified as one Nocardia, two Rhodococcus and two Gordonia strains, were able to degrade medium- and long-chain n-alkanes up to C36 as assessed by growth assays and gas chromatography-mass spectrometry analysis. Diverging alkane hydroxylase-encoding genes (alkB) were detected by PCR, using degenerated primers, in all the strains; multiple sequences were obtained from the Nocardia strain, while only one alkB gene was detected in the Rhodococcus and Gordonia strains. The majority of the alkB sequences were related to Rhodococcus alkB2, but none was identical to it. Conclusions: Actinomycetes might have a key role in bioremediation of n-alkane-contaminated sites under dry, resource-limited conditions, such as those found in the Mediterranean shorelines. Significance and Impact of the Study: To our knowledge, this is the first study on the bioremediation potential in Mediterranean contaminated beaches.