Driving the adaptation of microbial communities of the thawing permafrost: Mobile genetic elements at play

Climate change is driving significant transformations in northern ecosystems, impacting the structure and functioning of these environments. Permafrost thaw results in the expansion of thermokarst ponds and lakes, which are known to contribute to greenhouse gas (GHG) emissions. Despite the recognition of a high microbial biodiversity in these environments, little is known about the adaptation mechanisms of these microbial communities. Mobile genetic elements like plasmids, could inflect their eco-evolutionary path, contributing to the adaptation of microbes transitioning from terrestrial to aquatic habitats.  This study investigates the role of plasmids in the evolutionary trajectory of these microbial communities using metagenomics. Samples were collected along soil-water continua (active layer, sediments and water) from thermokarst ponds in sporadic (Québec, Canada) and continuous (Nunavut, Canada) permafrost regions.  Among metagenomes collected in sporadic permafrost, preliminary analyses identified 524 contigs out of 253,146 (>1000 bp) as belonging to plasmids. They were particularly abundant in the bottom of the water ponds and in the interstitial water of the active layer. Plasmid beta-diversity was found to be distinct from taxonomic beta-diversity, indicating a unique ecological role. Current efforts are focused on identifying key functions encoded by these plasmids, including genes involved in nutrient cycles and GHG emissions. Preliminary findings suggest that plasmids contribute to the eco-evolutionary dynamics of microbial communities in the thawing permafrost.

Primary Presenter: Valentine Cyriaque, Institut National de la Recherche Scientifique (valentine.cyriaque@inrs.ca)

Authors:

Valentine Cyriaque, Institut National de la Recherche Scientifique  (valentine.cyriaque@inrs.ca)

Martial Leroy, Institut National de la Recherche Scientifique  (martial.leroy@inrs.ca)

Ruddy Wattiez, UMONS  (ruddy.wattiez@umons.ac.be)

Jérôme Comte, Institut National de la Recherche Scientifique  (jerome.comte@inrs.ca)