Characterization and complete genome of the marine Pseudoalteromonas phage PH103, isolated from the Yellow Sea, China

A new marine phage-host system was isolated and further purified from the surface water of the Yellow Sea, China, using the agar overlay method. The host bacterium was identified to be a strain of Pseudoalteromonas marina by its 16S rRNA gene sequence. The phage, named Pseudoalteromonas phage PH103, was characterized and identified by morphological examination, host infection properties, stability, host range, full genome sequencing and bioinformatics analysis. The morphology of phage PH103 demonstrated that the phage is a member of the Siphoviridae family. PH103 showed strong tolerance with a wide range of temperatures (0–60 °C) and pH (3−13). The genome sequencing and bioinformatics analysis found the genome to be 43,190 bp long, with an average GC content of 41.17%. Seventy six ORFs were predicted in the genome, with twenty assigned genes included in the function groups of the host interaction, DNA replication/recombination, DNA packaging/head formation, and phage tail/host recognition. 44.74% of the total genome had no homologous sequence matching, which indicates that phage PH103 is newly identified.