Feces of feedlot cattle contain a diversity of bacteriophages that lyse non-O157 Shiga toxin-producing Escherichia coli

Abstract

This study aimed to isolate and characterize bacteriophages that lyse non-O157 Shiga toxin-producing Escherichia coli (STEC) from cattle feces. Of 37 non-O157 STEC-infecting phages isolated, O26- (vB_EcoS_AXO26A, vB_EcoM_AYO26A, vB_EcoM_AYO26B), O103- (vB_EcoS_AXO103A, vB_EcoP_AYO103A), O111- (vB_EcoM_AXO111A, vB_EcoM_AYO111A), O121- (vB_EcoM_AXO121A, vB_EcoM_AXO121B) and O145- (vB_EcoM_AYO145A, vB_EcoM_AYO145B) targeting phages were further characterized. Transmission electron microscopy showed the 11 isolates belonged to 3 families and 6 genera: the families Myoviridae (types rV5, T4, ViI, O1), Siphoviridae (type T5) and Podoviridae (type T7). Genome size of the phages as determined by pulsed-field gel electrophoresis ranged from 38 to 197 kb. Excluding phages AXO26A, AYO103A, AYO145A and AYO145B, all other phages were capable of lysing more than one clinically important strain from serogroups of O26, O91, O103, O111, O113, O121 and O128, but none exhibited infectivity across all serogroups. Moreover, phages AYO26A, AXO121A and AXO121B were also able to lyse 4 common phage types of STEC O157:H7. Our findings show that a diversity of non-O157 STEC-infecting phages are harbored in bovine feces. Phages AYO26A, AYO26B, AXO103A, AXO111A, AYO111A, AXO121A and AXO121B exhibited a broad host range against a number of serogroups of STEC and have potential for the biocontrol of STEC in the environment.