title: Microbial ecology of an Antarctic hypersaline lake: genomic assessment of ecophysiology among dominant haloarchaea.
abstract: Deep Lake in Antarctica is a cold, hypersaline system where four types of haloarchaea representing distinct genera comprise >70% of the lake community: strain tADL ∼44%, strain DL31 ∼18%, Halorubrum lacusprofundi ∼10% and strain DL1 ∼0.3%. By performing comparative genomics, growth substrate assays, and analyses of distribution by lake depth, size partitioning and lake nutrient composition, we were able to infer important metabolic traits and ecophysiological characteristics of the four Antarctic haloarchaea that contribute to their hierarchical persistence and coexistence in Deep Lake. tADL is characterized by a capacity for motility via flagella (archaella) and gas vesicles, a highly saccharolytic metabolism, a preference for glycerol, and photoheterotrophic growth. In contrast, DL31 has a metabolism specialized in processing proteins and peptides, and appears to prefer an association with particulate organic matter, while lacking the genomic potential for motility. H. lacusprofundi is the least specialized, displaying a genomic potential for the utilization of diverse organic substrates. The least abundant species, DL1, is characterized by a preference for catabolism of amino acids, and is the only one species that lacks genes needed for glycerol degradation. Despite the four haloarchaea being distributed throughout the water column, our analyses describe a range of distinctive features, including preferences for substrates that are indicative of ecological niche partitioning. The individual characteristics could be responsible for shaping the composition of the haloarchaeal community throughout the lake by enabling selection of ecotypes and maintaining sympatric speciation.
authors.affiliation: School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sydney, New South Wales, Australia.
authors.forename: Timothy J
authors.initials: TJ
authors.lastname: Williams
authors.affiliation: School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sydney, New South Wales, Australia.
authors.forename: Michelle A
authors.initials: MA
authors.lastname: Allen
authors.affiliation: School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sydney, New South Wales, Australia.
authors.forename: Matthew Z
authors.initials: MZ
authors.lastname: DeMaere
authors.affiliation: Department of Energy Joint Genome Institute, Walnut Creek, CA, USA.
authors.forename: Nikos C
authors.initials: NC
authors.lastname: Kyrpides
authors.affiliation: Department of Energy Joint Genome Institute, Walnut Creek, CA, USA.
authors.forename: Susannah G
authors.initials: SG
authors.lastname: Tringe
authors.affiliation: Department of Energy Joint Genome Institute, Walnut Creek, CA, USA.
authors.forename: Tanja
authors.initials: T
authors.lastname: Woyke
authors.affiliation: School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sydney, New South Wales, Australia.
authors.forename: Ricardo
authors.initials: R
authors.lastname: Cavicchioli
mesh_terms: D018528:ATP-Binding Cassette Transporters / Q000235:genetics; D000864:Antarctic Regions; D050260:Carbohydrate Metabolism; D060146:Ecotype; D020745:Genome, Archaeal; D023281:Genomics; D006216:Halobacteriaceae / Q000145:classification / Q000235:genetics / Q000378:metabolism*; D060106:Lakes / Q000382:microbiology*; D009584:Nitrogen / Q000378:metabolism; D054712:Salinity
chemical_list: D018528:ATP-Binding Cassette Transporters; D009584:Nitrogen