Moreover, searching for other mutations among ribosomal genes revealed that all 427.1 strains harbour missense mutations in genes coding for the uL3, uS2, bS16 and uS19 ribosomal proteins and in the gene encoding elongation factor G, confirming that the ribosomal machinery is under selective pressure in the CF environment40. This evidence concerns the gene RPS15 and cystic fibrosis.