Location: Produce Safety and Microbiology ResearchTitle: Complete genome sequence of a natural Escherichia coli O145:H11 isolate that belongs to Phylo-group A
Submitted to: Genome Announcements
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/24/2018
Publication Date: 4/19/2018
Citation: Carter, M.Q., Pham, A.C. 2018. Complete genome sequence of a natural Escherichia coli O145:H11 isolate that belongs to Phylo-group A. Genome Announcements. 6:e000349-18. https://doi.org/10.1128/genomeA.00349-18.
Interpretive Summary: The Escherichia coli species comprises commensal strains residing naturally in intestinal tracts of their mammalian hosts as well as pathogenic strains causing diverse intestinal and extra-intestinal infections in humans and animals. Shiga toxin-producing Escherichia coli (STEC) serotype O145, one of the major non-O157 serotypes associated with severe human disease, has evolved independently via multiple lineages. To gain insight into evolution of STEC O145, we complete the genome sequence of strain RM14721, an environmental strain isolated originally from wildlife feces near a leafy greens-growing region in Yuma, Arizona. This strain was initially positive in genes encoding Shiga toxin 1 (Stx1); however, in the subsequent cultures, stx1 genes were not detected by PCR, implying this strain may have harbored an unstable Stx1-encoding prophage. The genome of strain RM14721 is smaller than that of any known STEC strains and composed of a 4,620,018 bp chromosome and a 106,432 bp plasmid. The serotype was confirmed to be O145:H11 by BLAST search. Phylogenetic analyses placed this strain in phylo-group A, an distinct lineage compared with other known STEC O145 strains, which mainly belong to phylo-groups E and B1. Although no shiga toxin genes were identified in the genome of RM14721, several putative integration sites for Stx-converting phages were identified, including Stx1-converting phage AU5Stx1 and Stx2-converting phages PA2 (Stx2a) and 1717 (Stx2c), indicating the potential of strain RM14721 to evolve to a STEC strain.
Technical Abstract: Escherichia coli O145:H11 strain RM14721 was originally isolated from wildlife feces near a leafy greens-growing region in Yuma, Arizona. This strain was initially positive in stx1; however, in the subsequent cultures, stx1 was not detected by PCR. Here we report the complete genome sequence and annotation of RM14721.