Enterobacteria Phage Ac3's Genome Annotation and Host Range Analysis Against the ECOR Reference Library

Host range analyses and genome sequencing/annotation of bacteriophage isolates allow more effective development of tools for applications in medicine, agriculture, and the environment and expand our understanding of phage biology. Here we present the complete sequence of phage Ac3's assembled and annotated genome (accession OK040907). Originally referred to simply as "3," Ac3 has previously been described as a T4-like bacteriophage belonging to the Myoviridae family in the Caudovirales order of tailed bacteriophages. Using a combination of spot tests and full plate plaque assays, Ac3's permissive and adsorptive host range were evaluated against the ECOR Reference Library; a panel of 72 Escherichia coli isolates meant to represent the diversity of E. coli. Spot assays revealed that Ac3 could adsorb to 43 of the 72 strains (59.7%), whereas plaque assays demonstrated Ac3's ability to complete replication within 27 of the 72 strains (37.5%). By overlaying spot test and plaque assay results, 16 of the 45 nonpermissive ECOR strains (35.5%) were highlighted as being able to support Ac3's adsorption and tail contraction, but not its replication. Further characterization of Ac3 is still needed, however, the study presented here provides a solid starting point for future research.