Genome reconstruction of centuries old E.coli using fragments extracted from an Italian mummy

An international team led by researchers at McMaster University, working in collaboration with the University of Paris Cité, has identified and reconstructed the first ancient genome of E. coli, using fragments extracted from the gallstone of a 16thcentury mummy.

The discovery is published online today in the journal Communications Biology.

E. coli is a major public health concern, causing significant death and morbidity, yet is not a source of pandemics. It is known as a commensal, a bacteria that resides within us and can act as an opportunistic pathogen infecting its host during periods of stress, underlying disease or immunodeficiency.

Its full evolutionary history remains a mystery, including when it acquired novel genes and antibiotic resistance, say researchers.

Unlike well-documented pandemics such as the Black Death, which lingered for centuries and killed as many as 200 million people worldwide, there are no historical records of deaths caused by commensals such asE. coli, though the impact on human health and mortality was likely tremendous.

Modern E. coli is commonly found in the intestines of healthy people and animals. While most forms are harmless, some strains are responsible for serious, sometimes fatal food poisoning outbreaks and bloodstream infections. The hardy and adaptable bacterium is recognized as especially resistant to treatment.

Having the genome of a 400-year-old ancestor to the modern bacterium provides researchers a point of comparison for studying how it has evolved and adapted since that time. 

Reference: Long, G.S., Klunk, J., Duggan, A.T. et al. A 16th century Escherichia coli draft genome associated with an opportunistic bile infection. Commun Biol 5, 599 (2022). https://doi.org/10.1038/s42003-022-03527-1.