WGS: E.coli populations sequencing. Strain dependent rate of evolution in the gut of lean and obese mice

compare the evolution of two phylogenetic distinct strains of Escherichia coli in healthy hosts and hosts with obesity caused by leptin deficiency. Using in vivo experimental evolution in wild-type and ob/ob mice we find that a human and mouse commensal E. coli evolve at a similar pace in the gut of obese mice, but the human strain accumulates mutations at a faster rate in the gut of lean mice. Differences in strain background fitness are more likely to explain the differences in rates of evolution than differences in microbiota composition, as the 16S RNA profiles are similar across host genetic backgrounds. Pool sequencing of evolving clones from each strain shows high parallel adaptive evolution at the nucleotide level in healthy and obese hosts.