Low-temperature bacterial viruses VR – a small but diverse group of E. coli phages

The complete genome sequences of four low-temperature Escherichia coli -specific tevenviruses, vb_EcoM-VR5, vb_EcoM-VR20, vb_EcoM-VR25 and vb_EcoM-VR26, were determined. Genomic comparisons including recently described genomes of vb_EcoM-VR7 and JS98 as well as phage T4 allowed the identification of two genetic groups that were consistent with defined host-range phenotypes. Group A included the broad-host-range phages vb_EcoM-VR5 and JS98, while group B included vb_EcoM-VR7, vb_EcoM-VR20, vb_EcoM-VR25 and vb_EcoM-VR26, which all had somewhat limited host ranges. All four sequenced phages had genomes that were similar in length (~170 kb) and GC content (~40 %), and, with the exception of vb_EcoM-VR5, at the nucleotide level, they were much more closely related to each other than either was to any other tevenvirus currently characterized. Nevertheless, the overall genome organization of vb_EcoM-VR5, vb_EcoM-VR20, vb_EcoM-VR25 and vb_EcoM-VR26 was comparable to that seen in tevenviruses.