title: Seasonal fluctuations in ionic concentrations drive microbial succession in a hypersaline lake community.
abstract: Microbial community succession was examined over a two-year period using spatially and temporally coordinated water chemistry measurements, metagenomic sequencing, phylogenetic binning and de novo metagenomic assembly in the extreme hypersaline habitat of Lake Tyrrell, Victoria, Australia. Relative abundances of Haloquadratum-related sequences were positively correlated with co-varying concentrations of potassium, magnesium and sulfate, but not sodium, chloride or calcium ions, while relative abundances of Halorubrum, Haloarcula, Halonotius, Halobaculum and Salinibacter-related sequences correlated negatively with Haloquadratum and these same ionic factors. Nanohaloarchaea and Halorhabdus-related sequence abundances were inversely correlated with each other, but not other taxonomic groups. These data, along with predicted gene functions from nearly-complete assembled population metagenomes, suggest different ecological phenotypes for Nanohaloarchaea and Halorhabdus-related strains versus other community members. Nucleotide percent G+C compositions were consistently lower in community metagenomic reads from summer versus winter samples. The same seasonal G+C trends were observed within taxonomically binned read subsets from each of seven different genus-level archaeal groups. Relative seasonal abundances were also linked to percent G+C for assembled population genomes. Together, these data suggest that extreme ionic conditions may exert selective pressure on archaeal populations at the level of genomic nucleotide composition, thus contributing to seasonal successional processes. Despite the unavailability of cultured representatives for most of the organisms identified in this study, effective coordination of physical and biological measurements has enabled discovery and quantification of unexpected taxon-specific, environmentally mediated factors influencing microbial community structure.
authors: Marine Biology Research Division, Scripps Institution of Oceanography, University of California, San Diego, La Jolla, CA, USA.
authors: Sheila
authors: S
authors: Podell
authors: 1] Department of Earth and Planetary Sciences, University of California, Berkeley, CA, USA [2] Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, CO, USA.
authors: Joanne B
authors: JB
authors: Emerson
authors: Department of Earth and Planetary Sciences, University of California, Berkeley, CA, USA.
authors: Claudia M
authors: CM
authors: Jones
authors: Marine Biology Research Division, Scripps Institution of Oceanography, University of California, San Diego, La Jolla, CA, USA.
authors: Juan A
authors: JA
authors: Ugalde
authors: School of Earth Sciences, Byrd Polar Research Center, Ohio State University, Columbus, OH, USA.
authors: Sue
authors: S
authors: Welch
authors: Department of Biological Sciences, University of Southern California, Los Angeles, CA, USA.
authors: Karla B
authors: KB
authors: Heidelberg
authors: 1] Department of Earth and Planetary Sciences, University of California, Berkeley, CA, USA [2] Department of Environmental Science, Policy, and Management, University of California, Berkeley, CA, USA.
authors: Jillian F
authors: JF
authors: Banfield
authors: 1] Marine Biology Research Division, Scripps Institution of Oceanography, University of California, San Diego, La Jolla, CA, USA [2] Division of Biological Sciences, University of California, San Diego, La Jolla, CA, USA.
authors: Eric E
authors: EE
authors: Allen
mesh_terms: D001105:Archaea / Q000145:classification / Q000302:isolation & purification* / Q000378:metabolism; D001419:Bacteria / Q000145:classification / Q000235:genetics / Q000302:isolation & purification*; D041963:Bacteroidetes / Q000145:classification / Q000302:isolation & purification* / Q000378:metabolism; D017753:Ecosystem; D006216:Halobacteriaceae / Q000145:classification / Q000302:isolation & purification* / Q000378:metabolism; D060106:Lakes / Q000737:chemistry / Q000382:microbiology*; D054892:Metagenome; D056186:Metagenomics; D008969:Molecular Sequence Data; D010802:Phylogeny; D054712:Salinity; D012621:Seasons; D014739:Victoria