A strain of E. coli that is a common cause of outbreaks of food poisoning in the United States has had its genome sequenced. E. coli strain EDL933 was first isolated in the 1980s but gained national attention in 1993 when it was linked to an outbreak of food poisoning from Jack-in-the-Box restaurants in the western United States.

The genome sequence for this historical strain was first published in 2001 but there were many gaps in the genome that could not be closed with the sequencing technology available then. The new sequence unveiled in the journal Genome Announcements is the full, complete sequence with no gaps. Their analysis includes jumping genes that can move around the same genome, sometimes causing damage to individual genes or enabling antibiotic resistance. 

"With a complete genome sequence, we can now pinpoint the precise location of all such elements, which might help to track and treat future outbreaks," said Ramy Aziz,senior author on the paper and a professor at Cairo University in Egypt, who led the research as a visiting scientist working in Bernhard Palsson's Systems Biology Research Group at UC San Diego. The team used a combination of sequencing data from instruments made by Pacific Biosciences and Illumina.  

Bioengineers have completed the genome sequencing of a particularly harmful strain of E. coli that has been tied to outbreaks of food poisoning. The circular map shows the completed sequence with lighter color regions representing gaps in a 2001 sequencing of the strain that have now been completed with current technology.  Credit: Systems Biology Research Group, UC San Diego

"New sequencing and assembly methods are enabling a full expose of pesky pathogens; there is no place to hide genetic characteristics anymore. The full genetic delineation of multiple pathogenic strains is likely to not only improve our understanding of their characteristics, but to find and exploit their vulnerabilities," said Palsson, a Professor of Bioengineering at UC San Diego.