Ecophysiological characterization of cultivable Antarctic psychrotolerant marine bacteria able to degrade hydrocarbons

The basic understanding of both the physiology and ecology of psychrotolerant Antarctic bacteria is a crucial step for the optimization of their biodegradative activity in cold environments. The detection of cold-adapted hydrocarbon-degrading bacteria in Antarctic seawaters is certainly of great interest for bioremediative purpose in oil polluted marine Antarctic systems, where the introduction of non native species is not allowed. This study focused on psychrotolerant marine bacteria inhabiting an Antarctic coastal area directly influenced by the human activity at the Italian Research Station (Terra Nova Bay). Fifty bacterial strains were isolated from hydrocarbon-degrading enrichment cultures obtained from seawater samples collected in the inlet Road Bay (Ross Sea). A preliminary Restriction Fragment Length Polymorphism (RFLP) analysis, carried out on 16S rDNA amplified via PCR using RSAI and AluI restriction enzymes, was applied to cluster the isolates according to the restriction profile they showed. One representative isolate per cluster was selected for further characterization; to elucidate their taxonomic position, conventional phenotypic and phylogenetic analyses were performed. Results led to the identification of the isolates as members of ten genera belonging to four phylogenetic groups: the alfa- and gamma-proteobacteria subdivisions, the gram-positive branch and the Cytophaga-Flexibacter-Bacteroides (CFB) phylum. Results indicate a high degree of biodiversity within the peculiar ecophysiological group of the hydrocarbon-degrading marine bacteria