This is a collaborative project between the University of Tennessee Knoxville, Princeton University, and Institute of Physicochemical and Biological Problems in Soil Science of the Russian Academy of Science to study “Genetic, phylogenetic, and functional microbial diversity in permanently frozen aquatic sediments over geological time”. Almost a quarter of the land surface area in Earth's Northern Hemisphere is covered by perennially frozen subsurface deposits, called permafrost, overlaid by seasonally thawed tundra soils, called active layer or cryosol. Permafrost and permafrost-affected soils are considered to be a major reservoir for stored organic carbon that could become accessible to microbial degradation. The current project expanded our understanding of the extant and extinct microbial communities in young to ancient permanently frozen sediments with respect to evolutionary trends over time, the low temperature survivability and adaptation to psychrophilic life style. Two research expeditions to the Siberian Kolyma-Indigirka Lowland undertaken during the project enabled to collect samples of freshwater and marine permafrost deposits that have existed for about 10 thousand to 1.1 million years long. This research extended dimensions of our knowledge about diversity of microscopic life forms in the oldest permafrost deposits and showed existence of indigenous microbial communities that stay viable and sustain metabolic adaptations in ancient permafrost exhibiting presence of unique genes involved in membrane stabilization and osmotic stress responses. These genes are consistent with adaptation to the anoxic, high ionic strength habitats proving that permafrost microorganisms could maintain life in cold environments of permafrost brine films. To show that permafrost system holds a diverse mixture of active, dormant, and truly extinct microorganisms, we used multiple methods based on cultivation, nucleic acid amplification, amino acid racemization coupled with metagenomic sequencing and bioinformatic approaches. Metagenomes and metagenome-assembled genomes (MAGs) were used to link relevant metabolic functions to different taxa in ancient permafrost from a range of freshwater and marine environments. During the project we extended a list of extant permafrost microorganisms adding microscopic live animals – nematode and rotifer – to Kingdoms of the Bacteria, Archaea, Fungi, Plantae, and Protista, representatives of those groups have been isolated alive from the Siberian permafrost. The current research resulted in publishing twenty five papers, and was presented at forty six domestic meetings and international conferences. During the award, two postdoctoral researchers were supported, one doctoral student successfully defended a PhD thesis, and twelve undergraduate students were trained. The project supported organization of three summer programs in molecular biology for high school students, and two professional development workshops for high school teachers. We created two YouTube videos about collection of permafrost core samples in Kolyma-Indigirka Lowland region, to extend public knowledge on Siberian permafrost area including tundra landscape and life of local people.

Last Modified: 11/28/2021
Modified by: Tatiana A Vishnivetskaya