Figure 4

Core and pan-genome calculations for S. suis. (A) S. suis core genome. Each point represents the number of genes conserved between genomes. They are plotted as a function of strain numbers (x). For each x, the number of independent measurements is 13!/[n! (13-n)!]. The blue line demonstrates the exponential decay model based on the mean value of conserved genes. The curve is fitted to the function C(x) = Ac x^-tc + yc. The best fit is obtained with correlation R2 = 0.993 for Ac = 880 ± 50, tc = 0.52 ± 0.06, yc = 1126 ± 55. (B) Decreasing number of new genes with sequential addition of new genomes. Numbers of new genes are calculated for all possible combinations and plotted as a function of strain numbers (x). The blue line demonstrates the exponential decay model based on the mean value of conserved genes. The curve is fitted to the function S(x) = As x-ts + ys. The best fit is obtained with correlation R2 = 0.995 for As = 489 ± 27, ts = 1.35 ± 0.09, ys = 82 ± 4. (C) S. suis pan-genome curve. The deduced pan-genome size P(x) = As (x-1) × ^-ts + ys × - ys + Ac + yc. The curve continues to increase because the pan-genome of S. suis is open.