ERC AdG SYMBEK (PI Puri Lopez-Garcia)

SYMBEK - Symbiotic interactions at the origin of eukaryotes

Recent advances in environmental microbiology, metagenomics and phylogenomics strongly suggest that the eukaryotic cell evolved from symbiotic consortia involving an Asgard archaeon and, at least, the alphaproteobacterial ancestor of the mitochondrion. However, many genes of prokaryotic origin in the last eukaryotic common ancestor appear to originate neither from archaea nor Alphaproteobacteria, suggesting that other bacteria (notably Deltaproteobacteria, including Myxococcota, Bdellovibrionota, Desulfobacterota and related GTDB phyla) may have contributed to eukaryogenesis as additional symbionts or gene donors.

Here, we will study the ecology of symbiotic microbial consortia involving Asgard archaea in a broad variety of microbial mats and oxygen-poor environments. In particular, we will combine metagenomics, phylogenomics, fluorescence-activated single-cell/consortium sorting, high-throughput microfluidics, diverse microscopy techniques and cultivation approaches to meet the following objectives:

i) identify the partners of Asgard archaea syntrophic consortia across ecosystems, determine whether they co-evolve and unravel their ecological preferences

ii) characterize the metabolic interactions and phenotypic properties of Asgard archaea symbiotic consortia in culture and/or from sorted consortia populations

iii) characterize the three-dimensional organization of Asgard archaea consortia and their spatial distribution in microbial mats

iv) identify potential bacterial symbiotic partners involved in eukaryogenesis, in addition to the mitochondrial alphaproteobacterial ancestor, and/or gene donors to the last eukaryotic common ancestor or its Asgard archaeal predecessor

Our results should substantially advance understanding of eukaryogenesis.