Genome sequencing of Escherichia coli phage UFJF_EcSW4 reveals a novel lytic Kayfunavirus species.

The Escherichia coli phage UFJF_EcSW4 was isolated from polluted stream water and showed clear lysis plaques on the host, measuring 0.67 ± 0.43 mm, with a titer of 9.57 ± 0.23 log PFU/ml. It demonstrated a very narrow host range, infecting only its host. Additionally, it has a short latent period of 9 min, a burst size of 49 PFU/infected cell, and stability over a wide range of pH, temperature, and free residual chlorine. The phage has a double-stranded DNA genome spanning 40,299 bp, with a GC content of 49.87% and short-direct terminal repeats (DTR) sequences of 286 bp. The UFJF_EcSW4 genome contains 55 genes, organized into functional modules with a unidirectional arrangement, regulated by 22 promoters (three from the phage and 19 from the host) and three Rho-independent terminators. Comparative analysis revealed that the UFJF_EcSW4 genome shares an average genomic similarity of 77.82% with the genome sequences of phages from the Kayfunavirus genus but does not surpass the 95% threshold necessary for species classification. Therefore, the UFJF_EcSW4 is a novel Kayfunavirus UFJF_EcSW4 species belonging to the Studiervirinae subfamily.

Supplementary information: The online version contains supplementary material available at 10.1007/s13205-024-04172-7.