In this effort to "seek out new life," the team's findings fell into three main areas. The first was the discovery of unexpected metabolic features. They observed certain traits in Archaea that previously only were seen in Bacteria and vice-versa. One such trait involves an enzyme that bacteria commonly use for creating space within their protective cell wall, which is needed so the cell can, for example, expand during cell division. As it rather generically cleaves the protective bacterial cell envelope, it needs to be very tightly regulated. For the first time, a group of Archaea was found to encode this potent enzyme and the authors hypothesize that Archaea may deploy it as a defense mechanism against attacking Bacteria.
The second contribution arising from the work was the correct reassignment, or binning, of data of some 340 million DNA fragments from other habitats to the proper lineage. This course correction provides insights into how organisms function in the context of a particular ecosystem as well as a much improved and more accurate understanding of the associations of newly discovered genes with resident life forms.
The third finding was the resolution of relationships within and between microbial phylathe taxonomic ranking between domain and classwhich led the team to propose two new superphyla, which are highly stable associations between phyla. The 201 genomes provided solid reference points, anchors for phylogenythe lineage history of organisms as they change over time. "Our single-cell genomes gave us a glimpse into the evolutionary relationships between uncultivated organisms - insights that extend beyond the single locus resolution of the 16S rRNA tree and are essential for studying bacterial and archaeal diversity and evolution,"
|Contact: David Gilbert|
DOE/Joint Genome Institute