Cultivating Asgards, eukaryotes’ closest relatives

Background

The origin of eukaryotes approximately two billion years ago was one of the most impactful evolutionary events in the history of life on Earth. This transition likely took place through the symbiosis of an archaeal host cell and an intracellular bacterium, which eventually became the mitochondrion. However, this topic has been difficult to study because of lack of information on close prokaryotic relatives of eukaryotes. 

Anno 2022, a mere 18500 prokaryotes, of which only ~600 are archaea, have been cultured. These numbers represent far less than 1% of all prokaryotic diversity inhabiting our planet, as revealed by the use deep sequencing techniques. Even after two centuries of cultivating microorganisms, the gap between who we know is out there and who can be cultured in the lab remains immense. 

One of the many lineages of which no pure cultivated representatives exist are the Asgard archaea. This recently discovered group has been identified as the closest archaeal relative of eukaryotes. Obtaining novel cultivated representatives and draft genomes of this lineage could thus broaden our current knowledge and insight in how eukaryotes came to be. 

Aims

At our lab, focus on finding Asgard archaea in the environment. We go to various places (e.g. Iceland, Denmark, Azores, Netherlands) to collect interesting samples which are screened for the presence of Asgard archaea, but also other interesting archaeal lineages (e.g. DPANN, Bathyarchaeota, Korarchaeota). The most interesting samples are then used to set up targeted (high throughput) isolation campaigns to enrich and purify these Archaea. We aim to obtain new cultivated representatives of all uncultured clades of the Asgard archaea to allow a better understanding of their lifestyle and to shed more light into the origin of eukaryotes. 

Additionally, we focus on the genomic potential of uncultured Archaea. From our in-house enrichments, we collect metagenomic data (i.e. Illumina and Nanopore sequencing) and use this to create metagenome-assembled genomes from the taxa of interest. By looking into these genomes and comparing them with other available genomes from public repositories, we aim to elucidate what they are capable of, shine a light into the origin of Eukarya and broaden our window on the fascinating world of Archaea.  

Techniques

• General cultivation techniques
• (Anaerobic) cultivation
• Cell sorting
• Flow cytometry
• Sequencing
• Bioinformatics techniques

BSc/MSc theses

Thesis projects are available for BSc or MSc students with interest in fieldwork (sampling), general lab work (i.e. DNA-extraction, PCR, Illumina and Nanopore sequencing), microbial cultivation, microbial ecology and bioinformatics. Experience with working on linux command line and programming (e.g. python, R) is appreciated but not necessary. If you want to experience field, lab and pc work, look no further, because MicEvo is the group for you!