MetaPangenomic analysis within the Thermococcales
Résumé
The Archaeal Thermococcales order comprises anaerobic hyperthermophilicorganisms, with some of them additionally barophilic. Based on the phylogeny of their 16SrRNA genes, Thermococcales have been ranked into three genera: Pyrococcus, Thermococcusand Palaeococcus [1]. These archaea all harbor small, fast evolving genomes and a number ofintegrated or self-replicating mobile genetic elements [2–4]. Due to the combined effort ofdifferent teams, several isolates are now genetically tractable and used as valid genetic modelsto investigate the extremophilic way of life.With our complete genomic sequencing of new Thermococcales genomes, the totalnumber of available Thermococcales genomes is now 114 complete, and 270 if we includedall NCBI available genomes and newly reconstructed MAGs. The different approaches usedin our deep comparative analysis concurred in unambiguously ranking all Thermococcalesgenomes into six genera, differing significantly from the current classification and 118species.This pangenomic analysis in the Thermococcales will be combined to the prediction ofthe metabolic pathways, in order to analyse the distribution of these different metabolicpathways at the scale of pangenomes and to understand the evolutionary history of thedifferent metabolic pathways by discussing their ancestral presence, their acquisition byhorizontal transfer events or their loss. Such analyses will make it possible to specify themetabolic particularities of the different species, genera and ancestor of the Thermococcales.