title: Community shift from phototrophic to chemotrophic sulfide oxidation following anoxic holomixis in a stratified seawater lake.
abstract: Most stratified sulfidic holomictic lakes become oxygenated after annual turnover. In contrast, Lake Rogoznica, on the eastern Adriatic coast, has been observed to undergo a period of water column anoxia after water layer mixing and establishment of holomictic conditions. Although Lake Rogoznica's chemistry and hydrography have been studied extensively, it is unclear how the microbial communities typically inhabiting the oxic epilimnion and a sulfidic hypolimnion respond to such a drastic shift in redox conditions. We investigated the impact of anoxic holomixis on microbial diversity and microbially mediated sulfur cycling in Lake Rogoznica with an array of culture-independent microbiological methods. Our data suggest a tight coupling between the lake's chemistry and occurring microorganisms. During stratification, anoxygenic phototrophic sulfur bacteria were dominant at the chemocline and in the hypolimnion. After an anoxic mixing event, the anoxygenic phototrophic sulfur bacteria entirely disappeared, and the homogeneous, anoxic water column was dominated by a bloom of gammaproteobacterial sulfur oxidizers related to the GSO/SUP05 clade. This study is the first report of a community shift from phototrophic to chemotrophic sulfide oxidizers as a response to anoxic holomictic conditions in a seasonally stratified seawater lake.
authors.affiliation: Department of Molecular Ecology, Max Planck Institute for Marine Microbiology, Bremen, Germany ppjevac@mpi-bremen.de.
authors.forename: Petra
authors.initials: P
authors.lastname: Pjevac
authors.affiliation: Center for Marine Research, Ruđer Bošković Institute, Rovinj, Croatia.
authors.forename: Marino
authors.initials: M
authors.lastname: Korlević
authors.affiliation: Department of Biogeochemistry, Max Planck Institute for Marine Microbiology, Bremen, Germany.
authors.forename: Jasmine S
authors.initials: JS
authors.lastname: Berg
authors.affiliation: Division for Marine and Environmental Research, Ruđer Bošković Institute, Zagreb, Croatia Institute of Geochemistry and Petrology, Swiss Federal Institute of Technology, Zürich, Switzerland.
authors.forename: Elvira
authors.initials: E
authors.lastname: Bura-Nakić
authors.affiliation: Division for Marine and Environmental Research, Ruđer Bošković Institute, Zagreb, Croatia.
authors.forename: Irena
authors.initials: I
authors.lastname: Ciglenečki
authors.affiliation: Department of Molecular Ecology, Max Planck Institute for Marine Microbiology, Bremen, Germany.
authors.forename: Rudolf
authors.initials: R
authors.lastname: Amann
authors.affiliation: Center for Marine Research, Ruđer Bošković Institute, Rovinj, Croatia Division of Materials Chemistry, Ruđer Bošković Institute, Zagreb, Croatia.
authors.forename: Sandi
authors.initials: S
authors.lastname: Orlić
mesh_terms: D000693:Anaerobiosis; D001419:Bacteria / Q000145:classification* / Q000302:isolation & purification*; D058448:Biota / Q000187:drug effects*; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D056186:Metagenomics; D008969:Molecular Sequence Data; D010084:Oxidation-Reduction; D052817:Phototrophic Processes; D012623:Seawater / Q000737:chemistry* / Q000382:microbiology*; D017422:Sequence Analysis, DNA; D013440:Sulfides / Q000378:metabolism*
chemical_list: D004269:DNA, Bacterial; D013440:Sulfides