Coloring in the tree of life

Metagenome sequencing presents an exciting new tool for assessing microbial diversity in complex, natural communities that cannot be cultured in the laboratory. Using metagenomics as a starting point, Bryant et al. (2007) have discovered a new thermophilic phototroph from a poorly characterized bacterial phylum with no previously known photosynthetic members, extending the range of photosynthesis into a new branch on the tree of life. This new organism, Candidatus Chloracidobacterium thermophilum, encompasses a melange of traits distinct from known phototrophs.