Analysis of E. faecium genome diversity. Estimates of new gene discovery rate (panel A), total E. faecium gene pool (pan-genome) (panel B) and core-genome size (panel C) are shown for increasing values of the number n of E. faecium genomes sequenced. Colored circles represent the number of new or core genes present when a particular genome is added to the subset of the remaining genomes. Grey circles represent the total gene repertoire for a random collection of organisms. Medians of the distributions are indicated by red diamonds. The curve for the estimation of the gene discovery rate is a least squares fit of the power law Fnew(n) = κnew n-αto medians. The curve for the estimation of the size of the E. faecium pan-genome is a least squares power law (Fpan(n) = κpan nγ) fit to the medians. The size of the core genome was estimated by fitting the exponential curve Fcore(n) = κcore exp[-n/τcore] + tgcore(θ) to medians.