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Report

Teaser, summary, work performed and final results

Periodic Reporting for period 2 - TACKLE (TACK Superphylum and Lokiarchaeota Evolution: Dissecting the Ecology and Evolution of Archaea to Elucidate the Prokaryote to Eukaryote Transition)

Teaser

Summary

The project addresses two fundamental questions about the early evolution of life forms and about ecological strategies of microorganisms:

1) How did microorganisms that originated from hot springs succeed in conquering oxic and lower temperature environments on an early Earth?
2) How did complex multicellular organisms (plants and animals) arise from single celled microorganisms?

The major objective of this proposal is to better characterize two groups of Archaea which both mark these major evolutionary and ecological transitions in the evolution of microorganisms. The first group are Asgard archaea (formerly Lokiarchaeota) that are considered to represent the closest living prokaryotic relatives of eukaryotes (higher organisms). The second group are Thaumarchaeota that represent the only group of Archaea which have successfully radiated into moderate oxic environments.

Work performed

Novel habitats of Asgard archaea have been discovered and genomes have been analysed from large metagenomic data and from enrichment cultures that gave rise to novel hypotheses about their energy metabolism. In particular, we hypothesize from our data that Asgard archaea could gain energy by degrading halogenated compounds under anaerobic conditions.
A thermophilic Thaumarchaeote has been obtained in pure culture and together with 38 further Thaumarchaeota genomes was used to reconstruct the evolution and ecological adaptations of this group. The analysis revealed that the secret of the ecological success of Thaumarchaeota mostly lies in the constant acquisition of features coping with the increasing stress caused by elevated amounts of oxygen in moderate environments.

Final results

We expect to get deeper insights into the cellular, physiological, biochemical and genomic features of Thaumarchaeota and Lokiarchaetoa. This will shed light on their contribution to the early evolution of microorganisms as well as of complex organisms, such as plants and animals.