Defining the functional potential and active community members of a sediment microbial community in a high-arctic hypersaline subzero spring

• Published in: Applied and Environmental Microbiology
• Main Authors: Lay, C.-Y., Mykytczuk, N.C.S., Yergeau, É., Lamarche-Gagnon, G., Greer, C.W., Whyte, L.G.
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2013
• Subjects: Metagenomic analysis; Microbial communities; Microbial components; Microbial populations; Oligotrophic conditions; Permafrost environment; Stress response genes; Sub-zero temperatures; Ammonia; Genes; Metabolism; Methane; Microorganisms; RNA; Sulfur; Sulfur compounds; complementary DNA; primer DNA; RNA 16S; adaptation; discharge; environmental stress; enzyme activity; fluvial deposit; genetic analysis; hypersaline environment; microbial community; nutrient cycling; oxidation; population structure; terrestrial ecosystem; archaeon; Arctic; Bacteroidetes; cold; cyanobacterium; DNA sequence; genetics; metagenome; microbiology; molecular genetics; natural spring; nucleotide sequence; Proteobacteria; salinity; sediment; Archaea; Arctic Regions; Base Sequence; Cold Temperature; Cyanobacteria; DNA Primers; DNA; Complementary; Geologic Sediments; Molecular Sequence Data; Natural Springs; Ribosomal; 16S; Sequence Analysis; Canada; permafrost
• Online Access: https://doi.org/10.1128/AEM.00153-13; https://nrc-publications.canada.ca/eng/view/object/?id=10066444-a0de-4d4f-8826-203bb06c265a; https://nrc-publications.canada.ca/fra/voir/objet/?id=10066444-a0de-4d4f-8826-203bb06c265a

The Lost Hammer (LH) Spring is the coldest and saltiest terrestrial spring discovered to date and is characterized by perennial discharges at subzero temperatures (-5°C), hypersalinity (salinity, 24%), and reducing (≈-165mV), microoxic, and oligotrophic conditions. It is rich in sulfates (10.0%, wt/wt), dissolved H2S/sulfides (up to 25ppm), ammonia (≈381μM), and methane (11.1g day-1). To determine its total functional and genetic potential and to identify its active microbial components, we performed metagenomic analyses of the LH Spring outlet microbial community and pyrosequencing analyses of the cDNA of its 16S rRNA genes. Reads related to Cyanobacteria (19.7%), Bacteroidetes (13.3%), and Proteobacteria (6.6%) represented the dominant phyla identified among the classified sequences. Reconstruction of the enzyme pathways responsible for bacterial nitrification/ denitrification/ammonification and sulfate reduction appeared nearly complete in the metagenomic data set. In the cDNA profile of the LH Spring active community, ammonia oxidizers (Thaumarchaeota), denitrifiers (Pseudomonas spp.), sulfate reducers (Desulfobulbus spp.), and other sulfur oxidizers (Thermoprotei) were present, highlighting their involvement in nitrogen and sulfur cycling. Stress response genes for adapting to cold, osmotic stress, and oxidative stress were also abundant in the metagenome. Comparison of the composition of the functional community of the LH Spring to metagenomes from other saline/ subzero environments revealed a close association between the LH Spring and another Canadian high-Arctic permafrost environment, particularly in genes related to sulfur metabolism and dormancy. Overall, this study provides insights into the metabolic potential and the active microbial populations that exist in this hypersaline cryoenvironment and contributes to our understanding of microbial ecology in extreme environments. © 2013, American Society for Microbiology. Peer reviewed: Yes NRC publication: Yes