Full Name
Msc Annie Nguyen
Job Title
graduate student
University of Calgary
City (Work Address)
State/Province/County (Work Address)
Abstract Title
Genomic and physiological characterization of six Shiga toxin-producing Escherichia coli-infecting phages isolated from commercial feedlots in Alberta
Abstract Summary
Despite intensive control measures introduced to food processing facilities, emergence and persistence of Shiga toxin-producing Escherichia coli (STEC) continually challenges the food safety system worldwide. Bacteriophages are virus that specifically infect bacteria and show great potential in biocontrol of STEC in food supply chain. This study was to biologically and genomically characterize six STEC phages including AHF125, AXO26A, AXO45B and AXO103A, AXO103B and AXO103C isolated from cattle, Alberta. Excluding AXO45B and AXO26A, all other phages were capable of lysing more than 1 strains from the top 6 serogroups of O26, O45, O103, O111, O121, and O145. Moreover, AXO103B were able to lyse 4 common phage types of O157. Among the phages, AHF125 displayed the highest virulence (v= 0.77) against its host. Additionally, phage adsorption rate constant (k) of the phages were similar (5.2x10-10 ml/min − 2.2x10-9 ml/min). Based on genomic and morphological data, they belonged to Tequintavirus genus. All six phages contain a 110 kb dsDNA, encoding 150 – 163 genes and 22-24 tRNAs. All phage genomes were highly identical (92.5% identity) to O157 phage AKFV33, but their tail fibers (TFP) and receptor binding proteins (RBP), responsible for host range, differed. For example, TFP and RBP of AXO45B were only 19.9% and 30.3 % identical to their counterparts of AKFV33. No virulence, antibiotic-resistant, and lysogenic genes were detected form any phage genome. The findings provide valuable insight into genomic and physiological features of Tequintavirus that may be used to prevent STEC from entering food supply chain.