Festive Microbe Contest. Check website for further information.
Abstract:
Life as we know it depends on liquid water. Recent evidence indicates that not only did ancient Mars once have a vast network of surface waters, but that liquid water potentially could persist in the Martian subsurface to this day. Study of analogue environments, or environments with environmental conditions similar to those on ancient or extant Mars, provides insights into the potential life forms that could exist in on Mars and other worlds. Lost Hammer Spring, located on Axel Heiberg Island in the Canadian high Arctic, is one of the coldest and saltiest terrestrial springs discovered to date, the coldest known terrestrial methane seep, and a close analogue of putative Martian waters. It perennially discharges anoxic (<1 ppm dissolved oxygen), sub-zero (~−5 °C), and hypersaline (~24% salinity) brines from the subsurface through up to 600 m of permafrost. Using a multi-omics approach utilizing metagenome, metatranscriptome, and single-amplified genome sequencing, we revealed an active microbial community in the spring sediments utilizing primarily inorganic compounds (hydrogen sulfide, hydrogen, carbon dioxide) as energy and carbon sources, driven inpart by sulfide-oxidizing bacteriascavenging trace oxygen. These results demonstrated Mars-relevant metabolisms including sulfide oxidation, sulfate reduction, anaerobic oxidation of methane, and oxidation of trace gases (hydrogen, carbon monoxide) detected under anoxic, hypersaline, and sub-zero ambient conditions, providing evidence that similar extant microbial life could potentially survive in similar habitats on Mars.