Characterization of Two New Shiga Toxin-Producing Escherichia coli O103-Infecting Phages Isolated from an Organic Farm

Abstract

Shiga toxin-producing Escherichia coli (STEC) O103 strains have been recently attributed to various foodborne outbreaks in the United States. Due to the emergence of antibiotic-resistant strains, lytic phages are considered as alternative biocontrol agents. This study was to biologically and genomically characterize two STEC O103-infecting bacteriophages, vB_EcoP-Ro103C3lw (or Ro103C3lw) and vB_EcoM-Pr103Blw (or Pr103Blw), isolated from an organic farm. Based on genomic and morphological analyses, phages Ro103C3lw and Pr103Blw belonged to Autographiviridae and Myoviridae families, respectively. Ro103C3lw contained a 39,389-bp double-stranded DNA and encoded a unique tail fiber with depolymerase activity, resulting in huge plaques. Pr103Blw had an 88,421-bp double-stranded DNA with 26 predicted tRNAs associated with the enhancement of the phage fitness. Within each phage genome, no virulence, antibiotic-resistant, and lysogenic genes were detected. Additionally, Ro103C3lw had a short latent period (2 min) and a narrow host range, infecting only STEC O103 strains. By contrast, Pr103Blw had a large burst size (152 PFU/CFU) and a broad host range against STEC O103, O26, O111, O157:H7, and Salmonella Javiana strains. Furthermore, both phages showed strong antimicrobial activities against STEC O103:H2 strains. The findings provide valuable insight into these two phages’ genomic features with the potential antimicrobial activities against STEC O103.

A New Kayfunavirus-like Escherichia Phage vB_EcoP-Ro45lw with Antimicrobial Potential of Shiga Toxin-Producing Escherichia coli O45 Strain

“…Later, the samples were loaded into a MiSeq Reagent Kit v2 (500-cycle) and sequenced on MiSeq platform (Illumina, San Diego, CA, USA), generating approximately 14 million 2 × 250 bp paired-end reads. The updated assembly and annotation were generated using the previous methods [ 21 ] and deposited in National Center for Biotechnology Information (NCBI) database. Briefly, raw sequence reads were subjected to FASTQC and trimming via Trimmomatic with a setting of Q30.…”

Application of a novel lytic phage vB_EcoM_SQ17 for the biocontrol of Enterohemorrhagic Escherichia coli O157:H7 and Enterotoxigenic E. coli in food matrices

“…However, in a phage cocktail, the combination of several phages may lead to the recombination and antagonism between phage members, not to mention the increased cost of preparation of the cocktail (Son et al, 2018;Dion et al, 2020;Minh et al, 2020). Therefore, as a complementary method, phages with a broad host range are also under development for phage-based biocontrol of foodborne pathogens (Hagens and Loessner, 2010;Zhang et al, 2021). Along these lines, studies of phages for food application to effectively reduce EHEC O157:H7 contamination have been reported, including phages BECP10, PE37, JN01, and HY01 (Heyn et al, 2016;Son et al, 2018;Li et al, 2021;Park and Park, 2021).…”

Characterization of polyvalent Escherichia phage Sa157lw for the biocontrol potential of Salmonella Typhimurium and Escherichia coli O157:H7 on contaminated mung bean seeds

“…Later, the samples were loaded to a MiSeq Reagent Kit v2 (500-cycle) and sequenced on the MiSeq platform (Illumina, San Deigo, CA, USA), generating approximately 14 million 2 × 250-bp paired-end reads. The updated annotation was generated using previously reported methods ( Zhang et al, 2021 ) and deposited in National Center for Biotechnology Information (NCBI) database. Briefly, raw sequence reads were subjected to FASTQC and trimming via Trimmomatic with the setting of Q30.…”

“…The bacterial challenge assay was performed to measure the effects of phage Sa157lw with different MOIs on bacterial growth based on bacterial optical density at a wavelength of 600 nm (OD 600 ) as previously described with minor change ( Zhang et al, 2021 ). In brief, fresh bacterial culture of E. coli O157:H7 (ATCC 35150) or Salmonella Typhimurium (ATCC 14028) was prepared in TSB at 37°C overnight and further diluted in TSB to 1 × 10 6 CFU/ml.…”