Location: Meat Safety and QualityTitle: Comparative genomics of Escherichia coli serotype O55:H7 using complete closed genomes
Submitted to: Microorganisms
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/23/2022
Publication Date: 7/30/2022
Citation: Weinroth, M.D., Bono, J.L. 2022. Comparative genomics of Escherichia coli serotype O55:H7 using complete closed genomes. Microorganisms. 10(8): Article 1545. https://doi.org/10.3390/microorganisms10081545.
Interpretive Summary: Shiga toxin-producing Escherichia coli (STEC) O157:H7 is a foodborne pathogen that can cause mild to severe foodborne illness in humans. To better understand how STEC O157:H7 came to be, we evaluated complete closed genomes with its most common related bacteria; E. coli O55:H7. We found that while these two close relatives share many of the same genes, there is also sequence variation in some key areas as well as differences in overall genome architecture. Finally, we proposed a new step in the current proposed evolution of STEC O157:H7 from E. coli O55:H7. These newly publicly released genomes will allow a more complete understanding of the evolution of STEC O157:H7 from E. coli O55:H7 and help us better understand and control this foodborne pathogen.
Technical Abstract: Escherichia coli O55:H7 is a human foodborne pathogen and is recognized as the progenitor strain of E. coli O157:H7. While this strain is important from a food safety and genomic evolution standpoint, much of the genomic diversity of E. coli O55:H7 has been demonstrated using draft genomes. Here, we combine the four publicly available E. coli O55:H7 closed genomes with six newly sequenced closed genomes to provide context to this strain’s genomic diversity. We found significant diversity within the 10 E. coli O55:H7 strains that belonged to three different sequence types. The prophage content was about 10% of the genome, with three prophages common to all strains and seven unique to one strain. Overall, there were 492 insertion sequences identified within the six new sequence strains, with each strain on average containing 75 insertions (range 55 to 114). A total of 31 plasmids were identified between all isolates (range 1 to 6), with one plasmid (pO55) having an identical phylogenetic tree as the chromosome. The release and comparison of these closed genomes provides new insight into E. coli O55:H7 diversity and its ability to cause disease in humans.