The availability of genomic data from uncultured microbial lineages from a wide variety of environments is dramatically changing our view of microbial diversity. Recently, these techniques have brought to light a huge number of bacterial groups that, together with previously reported sequences, were used to define the Candidate Phyla Radiation (CPR).The CPR may constitute up to 50% of all bacterial diversity on Earth, yet it remains largely uncharacterized. This project will unite the complementary expertise of the Gribaldo (phylogenomics, evolutionary microbiology, Institut Pasteur) and...