title: Microbial community composition and diversity in Caspian Sea sediments.
abstract: The Caspian Sea is heavily polluted due to industrial and agricultural effluents as well as extraction of oil and gas reserves. Microbial communities can influence the fate of contaminants and nutrients. However, insight into the microbial ecology of the Caspian Sea significantly lags behind other marine systems. Here we describe microbial biomass, diversity and composition in sediments collected from three sampling stations in the Caspian Sea. Illumina sequencing of 16S rRNA genes revealed the presence of a number of known bacterial and archaeal heterotrophs suggesting that organic carbon is a primary factor shaping microbial communities. Surface sediments collected from bottom waters with low oxygen levels were dominated by Gammaproteobacteria while surface sediments collected from bottom waters under hypoxic conditions were dominated by Deltaproteobacteria, specifically sulfate-reducing bacteria. Thaumarchaeota was dominant across all surface sediments indicating that nitrogen cycling in this system is strongly influenced by ammonia-oxidizing archaea. This study provides a baseline assessment that may serve as a point of reference as this system changes or as the efficacy of new remediation efforts are implemented.
authors.affiliation: Department of Civil and Environmental Engineering, University of Tennessee, 37996-2313 Knoxville, TN Center for Environmental Biotechnology, University of Tennessee, 37996-1605 Knoxville, TN nagissa.m@gmail.com.
authors.forename: Nagissa
authors.initials: N
authors.lastname: Mahmoudi
authors.affiliation: BioSciences Division, Oak Ridge National Laboratory, 37831-6038 Oak Ridge, TN.
authors.forename: Michael S
authors.initials: MS
authors.lastname: Robeson
authors.affiliation: Department of Chemistry, University of Tennessee, 37996-1600 Knoxville, TN.
authors.forename: Hector F
authors.initials: HF
authors.lastname: Castro
authors.affiliation: Department of Civil and Environmental Engineering, University of Tennessee, 37996-2313 Knoxville, TN Center for Environmental Biotechnology, University of Tennessee, 37996-1605 Knoxville, TN.
authors.forename: Julian L
authors.initials: JL
authors.lastname: Fortney
authors.affiliation: Department of Civil and Environmental Engineering, University of Tennessee, 37996-2313 Knoxville, TN Center for Environmental Biotechnology, University of Tennessee, 37996-1605 Knoxville, TN.
authors.forename: Stephen M
authors.initials: SM
authors.lastname: Techtmann
authors.affiliation: Department of Civil and Environmental Engineering, University of Tennessee, 37996-2313 Knoxville, TN Center for Environmental Biotechnology, University of Tennessee, 37996-1605 Knoxville, TN.
authors.forename: Dominique C
authors.initials: DC
authors.lastname: Joyner
authors.affiliation: Department of Earth and Planetary Sciences, University of Tennessee, 37996-1410 Knoxville, TN.
authors.forename: Charles J
authors.initials: CJ
authors.lastname: Paradis
authors.affiliation: Center for Environmental Biotechnology, University of Tennessee, 37996-1605 Knoxville, TN.
authors.forename: Susan M
authors.initials: SM
authors.lastname: Pfiffner
authors.affiliation: Department of Civil and Environmental Engineering, University of Tennessee, 37996-2313 Knoxville, TN BioSciences Division, Oak Ridge National Laboratory, 37831-6038 Oak Ridge, TN Center for Environmental Biotechnology, University of Tennessee, 37996-1605 Knoxville, TN Department of Earth and Planetary Sciences, University of Tennessee, 37996-1410 Knoxville, TN Department of Microbiology, University of Tennessee, 37996-0845 Knoxville, TN.
authors.forename: Terry C
authors.initials: TC
authors.lastname: Hazen
mesh_terms: D001105:Archaea / Q000235:genetics; D001419:Bacteria / Q000235:genetics; D001483:Base Sequence; D044822:Biodiversity; D018533:Biomass; D019641:DNA, Archaeal / Q000235:genetics; D004269:DNA, Bacterial / Q000235:genetics; D004463:Ecology; D019015:Geologic Sediments / Q000382:microbiology*; D059013:Microbial Consortia / Q000235:genetics*; D009792:Oceans and Seas; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA; D014876:Water Pollution
chemical_list: D019641:DNA, Archaeal; D004269:DNA, Bacterial; D012336:RNA, Ribosomal, 16S
keywords: Caspian Sea; Illumina; PLFA; archaea; bacteria; marine sediments