A phylogeny-driven genomic encyclopaedia of Bacteria and Archaea

Abstract

The bacterial and archaeal genomes that have been sequenced to date were chosen for sequencing based mainly on their physiology, which is fine but has resulted in a distinct phylogenetic bias. An alternative approach has been taken in the Genomic Encyclopedia of Bacteria and Archaea (GEBA) project, which advocates choosing genomes based on the organism's phylogenetic position, with the aim filling in the gaps in sequencing along on bacterial and archaeal branches of the tree of life. The value of this approach has been demonstrated by a pilot study of the genome sequences of 56 culturable species selected to maximize phylogenetic coverage. Analysis of the sequences provides insights into phylogenetics, protein function and genome annotation. There are now nearly 1,000 completed bacterial and archaeal genomes available, but as most of them were chosen for sequencing on the basis of their physiology, the data are limited by a highly biased phylogenetic distribution. To explore the value added by choosing microbial genomes for sequencing on the basis of their evolutionary relationships, the genomes of 56 species of Bacteria and Archaea selected to maximize phylogenetic coverage are now sequenced and analysed. Sequencing of bacterial and archaeal genomes has revolutionized our understanding of the many roles played by microorganisms1. There are now nearly 1,000 completed bacterial and archaeal genomes available2, most of which were chosen for sequencing on the basis of their physiology. As a result, the perspective provided by the currently available genomes is limited by a highly biased phylogenetic distribution3,4,5. To explore the value added by choosing microbial genomes for sequencing on the basis of their evolutionary relationships, we have sequenced and analysed the genomes of 56 culturable species of Bacteria and Archaea selected to maximize phylogenetic coverage. Analysis of these genomes demonstrated pronounced benefits (compared to an equivalent set of genomes randomly selected from the existing database) in diverse areas including the reconstruction of phylogenetic history, the discovery of new protein families and biological properties, and the prediction of functions for known genes from other organisms. Our results strongly support the need for systematic ‘phylogenomic’ efforts to compile a phylogeny-driven ‘Genomic Encyclopedia of Bacteria and Archaea’ in order to derive maximum knowledge from existing microbial genome data as well as from genome sequences to come.