Characterization of marine bacteriophages isolated from the Alboran Sea (Western Mediterranean)

It has been shown recently that viruses are important agents for the bacterial mortality in marine ecosystems. In this study, 26 bacteriophages were isolated from the Alboran Sea and subsequently characterized in order to determine the diversity of the viral community in this marine environment. All the host bacteria were Gram-negative motile rods, and were unable to grow in media without NaCl. Bacteriophages contained DNA, were not sensitive to chloroform (except phage 16), and showed a close and narrow host range. Morphological studies revealed that most of them were included in two of the three tailed families of the Caudovirales order (viruses belonging to the Podoviridae family were not observed). All bacteriophages had icosahedral heads, the most abundant size class being those ranging from 30 to 60 nm in diameter. The protein profiles of viral clones showed higher variability than that observed by morphological analyses. Phages were grouped in 11 classes on the basis of the protein patterns. In short, phage-host systems analysed in this study are a diverse group and representative of the marine viral community. For this reason, they can be considered as models in studies on the interaction between viral and bacterial communities.