The Discovery of phiAGATE, A Novel Phage Infecting Bacillus pumilus, Leads to New Insights into the Phylogeny of the Subfamily Spounavirinae

The Bacillus phage phiAGATE is a novel myovirus isolated from the waters of Lake Goreckie (a eutrophic lake in western Poland). The bacteriophage infects Bacillus pumilus, a bacterium commonly observed in the mentioned reservoir. Analysis of the phiAGATE genome (149844 base pairs) resulted in 204 predicted protein-coding sequences (CDSs), of which 53 could be functionally annotated. Further investigation revealed that the bacteriophage is a member of a previously undescribed cluster of phages (for the purposes of this study we refer to it as “Bastille group”) within the Spounavirinae subfamily. Here we demonstrate that these viruses constitute a distinct branch of the Spounavirinae phylogenetic tree, with limited similarity to phages from the Twortlikevirus and Spounalikevirus genera. The classification of phages from the Bastille group into any currently accepted genus proved extremely difficult, prompting concerns about the validity of the present taxonomic arrangement of the subfamily.