Whole-Genome Sequences of Phages p000v and p000y, Which Infect the Bacterial Pathogen Shiga-Toxigenic Escherichia coli

Abstract

We report here the genome sequences and morphological characterizations of phages p000v and p000y, which infect the bacterial pathogen Shiga-toxigenic Escherichia coli O157:H7 and which are potential candidates for phage therapy against such pathogens.

FIG 1

Morphological and genetic characterization of phages p000v and p000y. Whole-genome comparison of p000v, p000y, and E. coli phage T4 reveals that p000v and p000y are T4-like due to their high average nucleotide identity (ANI) shared with T4. For T4, GenBank sequence AF158101 was used. Shown via EasyFig 2.2.2 (10) are the percent protein similarities, obtained via a tblastx search (16) with an e value of 0.001, and their average nucleotide identities. Next to each genome is a transmission electron microscopy (TEM)-derived micrograph, which reveals that both phages have a Myoviridae morphology. TEM was performed at The Ohio State University (OSU) Campus Microscopy and Imaging Facility (CMIF) on an FEI Tecnai G2 Spirit TEM at an acceleration voltage of 80 kV, following a modified protocol (17). Samples were derived from 0.2-µm-filtered phage lysates that were concentrated with polyethylene glycol (p000v) and also purified with a CsCl (p000y) density gradient and dialyzed in phage buffer. For phage p000v, a 10-µl sample was deposited onto Formvar-coated 200-mesh copper TEM grids (Ted Pella, Inc., Redding, CA) and incubated for 30 min at room temperature. Grids were washed twice with distilled water and negatively stained with 10 µl of 2% uranyl acetate for 15 s. For p000y, a 200-µl sample was deposited onto the grids with an air-driven ultracentrifuge (Airfuge CLS, Beckman Coulter, Brea, CA), followed by negative staining as described.