A new Kayfunavirus-like Escherichia phage vB_EcoP-Ro45lw with antimicrobial potential of Shiga toxin-producing Escherichia coli O45 strain

Authors: SUN, XINCHENG - Zhengzhou University Of Light Industry; Liao, Yen-Te; ZHANG, YUJIE - Oak Ridge Institute For Science And Education (ORISE); Salvador, Alexandra; HO, KAN-JU - Forest Service (FS); Wu, Vivian

Submitted to: Microorganisms
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/23/2022
Publication Date: 12/27/2022
Citation: Sun, X., Liao, Y., Zhang, Y., Salvador, A., Ho, K., Wu, V.C. 2022. A new Kayfunavirus-like Escherichia phage vB_EcoP-Ro45lw with antimicrobial potential of Shiga toxin-producing Escherichia coli O45 strain. Microorganisms. 11(1). Article 77. https://doi.org/10.3390/microorganisms11010077.
DOI: https://doi.org/10.3390/microorganisms11010077

Interpretive Summary: Lytic bacteriophages (also known as phages) are considered a solution to resolve antibiotic-resistant issues. Non-O157 Shiga toxin-producing E. coli (STEC) strains caused many foodborne outbreaks; however, current interventions used in the food industry are not sufficiently effective against each type of the pathogen. This study focused on the genomic and biological characterization of a new lytic bacteriophage vB_EcoP-Ro45lw (or Ro45lw) and determining its biocontrol potential against pathogenic E. coli O45 strains. The results show that phage Sa45lw is a new short-tailed phage belonging to the Kayfunavirus genus, sharing no close evolutionary relationship with any reference phages. Additionally, no virulent, antibiotic-resistant, or lysogenic genes were found in the phage genome that could jeopardize the safety of phage application. The growth curve results indicate that phage Ro45lw has a short replication time (15 min) and a small burst size (55 phage particles per infected bacterial cell). Moreover, regardless of phage concentration, Ro45lw can effectively suppress the growth of both environmental and clinical E. coli O45 strains. The findings of this study demonstrate that phage Ro45lw has the antimicrobial potential mitigating pathogenic STEC O45 strains.

Technical Abstract: Lytic bacteriophages are re-considered as a solution to resolve antibiotic-resistant rampage. Despite frequent foodborne outbreaks caused by the top-six non-O157 Shiga toxin-producing Escherichia coli (STEC), current interventions used in the food industry are not sufficiently effective against each serogroup, particularly O45. Therefore, the objective was to characterize a new short-tailed phage as an alternative antimicrobial agent for STEC O45 strains. Phage Ro45lw belongs to the Kayfunavirus genus within the Autographiviridae family and shares no close evolutionary relationship with any reference phages. Ro45lw contains a tail structure composed of a unique tail fiber and tail tubular proteins A and B, likely to produce enzymatic activity against bacterial cells besides structural function. Additionally, the phage genome does not contain virulent, antibiotic-resistant, or lysogenic genes. This phage has a latent period of 15 min with an estimated burst size of 55 PFU/CFU and is stable at a wide range of pH (pH4 to pH11) and temperatures (30 to 60 degree Celsius). Regardless of the MOIs (MOI=0.1, 1, and 10) used, Ro45lw has a strong antimicrobial activity against both environmental (E. coli O45:H-) and clinical (E. coli O45:H2) strains at 25 degree Celsius. These findings indicate that phage Ro45lw has antimicrobial potential in mitigating pathogenic STEC O45 strains.