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ARS Home » Pacific West Area » Albany, California » Western Regional Research Center » Produce Safety and Microbiology Research » Research » Publications at this Location » Publication #372241

Research Project: Ecology and Detection of Human Pathogens in the Produce Production Continuum

Location: Produce Safety and Microbiology Research

Title: Genomic characterization and potential pathogenetic analysis of Shiga toxin-converting bacteriophages induced from Shiga toxin-producing Escherichia coli strains.

item ZHANG, YUJIE - Shanghai Ocean University
item Liao, Yen-Te
item Salvador, Alexandra
item SUN, XIAOHONG - Shanghai Ocean University
item Wu, Vivian

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 1/31/2020
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Shiga toxin encoded by Stx genes in the prophage sequence contributes the major pathogenicity of Shiga toxin-producing Escherichia coli (STEC). Previous studies investigated the presence of Stx prophages from different STEC chromosomes by computational approaches. Nevertheless, studies regarding Stx-converting phages physically induced from the STEC host strains and examining their potential transduction as infectious agents to other commensal strains are lacking. Thus, the objectives of this study were to characterize two Stx-converting phages induced from STEC using whole-genome sequencing and to determine the diversity and potential transduction of Stx-converting phages. The DNAs of phage Lys8385Vzw and Lys19259Vzw were extracted and further subjected to whole-genome sequencing using Illumina Miseq. Subsequently, comparative genomic analyses were conducted to determine the diversity of phages and evaluate the potential bacterial hosts by comparing these two phages to the genomes of 13 Stx-converting phages and 10 STEC strains. The transduction of two phages was performed by infecting 3 non-pathogenic E. coli strains (WG5, DH5a, and MG1655) using spot test. Results showed that both phage Lys8385Vzw and Lys19259Vzw had double-stranded DNA, with a genome size of 50,953 bp and 61,072 bp, respectively. 44 of the 68 protein-coding genes (CDSs) in Lys8385Vzw and 38 of 85 CDSs in Lys19259Vzw were annotated as functional CDSs. The CDSs, including infection, lysis, pathogenic regulation in particularly, provided advantages to either phage or bacteria. Phylogenetic analysis showed the diversity of Stx-converting phages from STEC O157:H7 host strains. Additionally, the results showed Lys8385Vzw shared more than 70% coverage and 95% identity to the Stx prophage sequences in 5 clinical non-O157 STEC strains, whereas Lys19259Vzw shared 99% coverage and identity to the Stx prophage sequences in 5 STEC O157 strains from clinical and environmental samples, suggesting potentially phage-mediated transfer of virulence gene under different environment. The in vitro experiment showed both phages were able to lysogenize all selected strains to form new lysogeny. The finding of the study demonstrates the potential transduction of Stx-converting phages among different STEC strains. Additionally, the results will facilitate tracking and identification of the emergence of new STEC pathogens.