Arctic / Antarctic / Alpine

Metagenomics Untangles Metabolic Adaptations Of Antarctic Endolithic Bacteria At The Fringe Of Habitability

By Keith Cowing
Status Report
August 18, 2023
Filed under , , , ,
Metagenomics Untangles Metabolic Adaptations Of Antarctic Endolithic Bacteria At The Fringe Of Habitability
Maximum likelihood phylogenetic tree of [NiFe]-hydrogenase gene sequences obtained from our MAGs (n = 2433), with reference sequences obtained from the HydB and previous phylogenetic analysis. Branches and reference gene labels are colored according to the group of [NiFe]-hydrogenase. Bootstrap values >90% are depicted as filled circles on branches, with size reflecting value, and 1000 ultrafast bootstrap iterations applied. The phyla of the originating MAGs assembled in this study are displayed in a color-coded outer ring. In cases where RuBisCO large subunit gene/s co-occurred within these genomes, the proportion of forms present is indicated by external pie charts. —

Background: Endolithic niches offer an ultimate refuge, supplying buffered conditions for microorganisms that dwell inside rock airspaces. Yet, survival and growth strategies of Antarctic endolithic microbes residing in Earths’ driest and coldest desert remains virtually unknown.

Results: From 109 endolithic microbiomes, 4,539 metagenome-assembled genomes were generated, 49.3% of which were novel candidate bacterial species. We present evidence that trace gas oxidation and atmospheric chemosynthesis may be the prevalent strategies supporting metabolic activity and persistence of these ecosystems at the fringe of life and the limits of habitability.

Conclusions: These results represent the foundation to untangle adaptability at the edge of sustainability on Earth and on other dry Earth-like planetary bodies such as Mars.

a-c, Map of Antarctica (a) and sampling sites (Victoria Land, b; Peninsula, c) (red dots). d, Number of MAGs and their quality-based classification. e, Upper bar plot: number of unclassified OTUs. Bottom bar plot: number of species, genera, families, orders, classes and phyla. f, Phylogenetic tree of the 2,278 OTUs built from the multiple sequence alignment of 120 GTDB marker genes. Barplot in the outer circle indicates the number of samples in which each OTUs was found. g, Phylum-level Mash Screen multiplicity for each sample, indicating sequence coverage. Horizontal lines represent the median values. The occupancy value indicates the percentage of samples that contains the underlying phylum. h, Number of OTUs as a function of the number of rock samples. —



Explorers Club Fellow, ex-NASA Space Station Payload manager/space biologist, Away Teams, Journalist, Lapsed climber, Synaesthete, Na’Vi-Jedi-Freman-Buddhist-mix, ASL, Devon Island and Everest Base Camp veteran, (he/him) 🖖🏻