‘Geoarchaeote NAG1’ is a deeply rooting lineage of the archaeal order Thermoproteales rather than a new phylum

Recent cultivation-independent studies have revealed a considerable diversity of uncultured and uncharacterized archaeal lineages. The genomic characterization of these lineages will be instrumental in order to shed light on their physiology and ecological significance and to provide an overall insight on the genomic diversity and evolution of the archaeal domain of life. In a recent issue of The ISME Journal , Kozubal et al. (2012) have used a metagenomic approach to obtain the composite genome of members of a ‘novel archaeal group 1’ (NAG1), isolated from a high-temperature acidic iron mat in Yellowstone National Park. Based on phylogenetic analysis of selected marker genes, Kozubal et al. (2012) concluded that NAG1 represented a novel phylum (‘Geoarchaeota’) in the Domain Archaea.