Complete Genome Sequence Analysis of the Cold-active Siphoviridae Bacteriophage from Pseudomonas fluorescens

Phages are considered the most abundant and diverse biological entities on Earth. Although many phages have been isolated, most of this diversity remains completely unexplored. Recent advances in genome sequencing, however, have provided unprecedented glimpses into the virosphere. The lytic cold-active Siphoviridae bacteriophage VW6S, infecting the host Pseudomonas fluorescens W-6, was isolated from the Napahai plateau wetland in China. The newly sequenced phage VW6S contained double-stranded DNA with a genome size of 37,917 bp, an overall GC content of 56.90% and 52 open reading frames (ORFs). The genome was organized into several modules containing genes for packaging, structural proteins, replication/transcription, and cell lysis. The sequence contained 16 transcription terminators, no tRNAs. The lysis cassette of VW6S consisted of 4 proteins (holin protein, lysin protein and 2 putative spanins). This is the first report on cold-active SiphoviridaePseudomonas fluorescens bacteriophage genome sequencing.