Isolation and characterization of a novel Escherichia coli Kayfunavirus phage DY1.

Phage therapy has been revitalized since antibiotic resistance in bacteria is increasing. Compared with antibiotics, phages can target specific bacteria precisely, which requires more understanding of phage-host interactions by investigating different phages. Escherichia coli is a common pathogen with very high diversity. Based on the O antigens, E. coli can be classified into at least 183 serotypes and existing phages are far from being able to lyse all E. coli. Therefore, a novel phage specific to E. coli, named DY1, was identified and characterized to enhance our understanding of the phages of E. coli and expand the phage library. Phage DY1 belongs to the family Autographiviridae which is derived from Podoviridae. The genome of DY1 was determined to be 39,817 bp and comprises 54 putative open reading frames. Comparative genome and phylogenetic analysis demonstrated that DY1 was highly similar to phages belonging to the genus Kayfunavirus; however, the highest average nucleotide identity (ANI) values of DY1 with known phages was 0.82 suggesting that DY1 was a novel phage. Through stability tests, DY1 was very stable at temperatures ranging from 20 to 50 °C and pH levels from 5 to 11. Taken together, we report that phage DY1 is a novel Kayfunavirus phage with the potential for phage therapy.