Location: Produce Safety and Microbiology ResearchTitle: Characterization of three lytic bacteriophages as an antimicrobial agent for biocontrol of Shiga toxin-producing Escherichia coli O145
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 4/2/2020
Publication Date: N/A
Interpretive Summary: N/A
Technical Abstract: Introduction: Shiga toxin-producing E. coli (STEC) O145 is one of the most prevalent non-O157 serogroups associated with numerous produce outbreaks around the world, causing bloody diarrhea, urinary tract infections, kidney failure, and high mortality among immunocompromised population. Lytic phages are alternative antibacterial agents to minimize the emergence of antimicrobial-resistant strains. However, the information regarding the characterization of lytic phages for the control of STEC O145 is scarce. Objective: Thus, the objective of this study was to characterize three bacteriophages for the biocontrol potential of STEC O145 strains. Methods: Three lytic phages specific to STEC O145 strains were isolated from fecal samples (phage UDF145_1 and UDF145_2) and water sediment (phage Pr145T13lw). After purification, three phages were subjected to morphology characterization, host range tests against STEC O157 and top 6 non-O157, stx genes screening, and temperature susceptibility tests (50°C) for 24 hours. The antimicrobial activities of these phages were evaluated at MOI = 1 using a spectrophotometer. Results: Phages UDF145_2 and Pr145T13lw had a similar morphology belonging to Siphoviridae family whereas phage UDF145_1 belonged to Myoviridae family. The host range test revealed that phage Pr145T13lw had a wider host range, lytic against STEC O145, O111, O26, and generic E. coli strains (DH5'), than phages UDF145_1 and UDF145_2, which were lytic against STEC O145 and generic E. coli (ATCC13706) strains. Additionally, at MOI=1, phage Pr145T13lw rendered significantly higher antimicrobial effects against both outbreak and environmental STEC O145 strains than the other 2 phages. All three phages were stable at temperature ranging from 4°C to 50°C and did not harbor stx genes. Significance: The three phages, with different host ranges, are able to render strong lytic effects against STEC O145 strains, and their temperature stability could aid in the development of alternative biocontrol strategies for STEC O145 in the pre-harvest produce environment.