Figure 2
Amino acid usage differs between mesophilic, thermophilic and hyperthermophilic prokaryotes. Distribution of amino acid usage bias, ERK, across orthologous proteins for 5 species each of hyperthermophilic (optimal growth temperature ≥80° Celsius), thermophilic (50-80°), and mesophilic (≤50°) prokaryotes. All pairwise comparisons are statistically highly significant (Wilcoxon rank sum tests: p < 10-15). See Additional file 1: Supplemental Figure S3 for a correlated alternative measure of amino acid usage bias. Black: mesophiles; blue: thermophiles; red: hyperthermophiles.