Complete Genome Sequence of the Cold-Active Bacteriophage W-6A from Pseudomonas fluorescens

The cold-active bacteriophage W-6A, its host is Pseudomonas fluorescens, belonging to the Siphoviridae, was isolated from Napahai wetland in China. Sequence analysis revealed that the genome is 37,917 bp long, with an overall G＋C content of 56.90 mol%. A total of 58 open reading frames (ORFs) (12 on the forward strand and 46 on the reverse strand) were identified. The sequence contains 126 promoter binding sites, 16 transcription terminators, 5 inverted repeats, and no tRNAs. Phylogenetic analyses of complete genome revealed that W-6A is closely related to  Pseudomonas phage phi297 (NC016762). Of the 58 predicted ORFs, 37 were identified as encoding hypothetical proteins, and the remaining ORFs were classified into five functional groups, including structural proteins, DNA replications and transcription enzymes, DNA packing proteins, host lysis enzymes and other. ORF 17 shows a high sequence similarity to the Rha family transcriptional regulator protein from Pseudomonas fluorescens, From this information, we propose that the W-6A phage is at an intermediate phase in its co-evolution with its bacterial host. This is the first report of sequencing and characterization of any Pseudomonasfluorescence lytic cold-active bacteriophages from Napahai wetland region, and these observations add to our current knowledge about the co-evolution of bacteriophages and their hosts.

Keywords: genome sequence, cold-active，bacteriophage, Pseudomonas fluorescence