title: Microbial processes of the carbon and sulfur cycles in an ice-covered, iron-rich meromictic lake Svetloe (Arkhangelsk region, Russia).
abstract: Biogeochemical, isotope geochemical and microbiological investigation of Lake Svetloe (White Sea basin), a meromictic freshwater was carried out in April 2014, when ice thickness was ∼0.5 m, and the ice-covered water column contained oxygen to 23 m depth. Below, the anoxic water column contained ferrous iron (up to 240 μμM), manganese (60 μM), sulfide (up to 2 μM) and dissolved methane (960 μM). The highest abundance of microbial cells revealed by epifluorescence microscopy was found in the chemocline (redox zone) at 23-24.5 m. Oxygenic photosynthesis exhibited two peaks: the major one (0.43 μmol C L-1day-1) below the ice and the minor one in the chemocline zone, where cyanobacteria related to Synechococcus rubescens were detected. The maximum of anoxygenic photosynthesis (0.69 μmol C L-1day-1) at the oxic/anoxic interface, for which green sulfur bacteria Chlorobium phaeoclathratiforme were probably responsible, exceeded the value for oxygenic photosynthesis. Bacterial sulfate reduction peaked (1.5 μmol S L-1day-1) below the chemocline zone. The rates of methane oxidation were as high as 1.8 μmol CH4L-1day-1at the oxi/anoxic interface and much lower in the oxic zone. Small phycoerythrin-containing Synechococcus-related cyanobacteria were probably involved in accumulation of metal oxides in the redox zone.
authors.affiliation: Winogradsky Institute of Microbiology, Research Center of Biotechnology, Russian Academy of Sciences, Moscow, Russia.
authors.forename: Alexander S
authors.initials: AS
authors.lastname: Savvichev
authors.affiliation: Institute of Ecological Problems of the North, Ural Branch, Russian Academy of Sciences, Arkhangelsk, Russia.
authors.forename: Natalia M
authors.initials: NM
authors.lastname: Kokryatskaya
authors.affiliation: Institute of Ecological Problems of the North, Ural Branch, Russian Academy of Sciences, Arkhangelsk, Russia.
authors.forename: Svetlana A
authors.initials: SA
authors.lastname: Zabelina
authors.affiliation: Winogradsky Institute of Microbiology, Research Center of Biotechnology, Russian Academy of Sciences, Moscow, Russia.
authors.forename: Igor I
authors.initials: II
authors.lastname: Rusanov
authors.affiliation: Winogradsky Institute of Microbiology, Research Center of Biotechnology, Russian Academy of Sciences, Moscow, Russia.
authors.forename: Elena E
authors.initials: EE
authors.lastname: Zakharova
authors.affiliation: Winogradsky Institute of Microbiology, Research Center of Biotechnology, Russian Academy of Sciences, Moscow, Russia.
authors.forename: Elena F
authors.initials: EF
authors.lastname: Veslopolova
authors.affiliation: Winogradsky Institute of Microbiology, Research Center of Biotechnology, Russian Academy of Sciences, Moscow, Russia.
authors.forename: Olga N
authors.initials: ON
authors.lastname: Lunina
authors.affiliation: Institute of Bioengineering, Research Center of Biotechnology, Russian Academy of Sciences, Moscow, Russia.
authors.forename: Ekaterina O
authors.initials: EO
authors.lastname: Patutina
authors.affiliation: Institute of Bioengineering, Research Center of Biotechnology, Russian Academy of Sciences, Moscow, Russia.
authors.forename: Boris K
authors.initials: BK
authors.lastname: Bumazhkin
authors.affiliation: Institute of Bioengineering, Research Center of Biotechnology, Russian Academy of Sciences, Moscow, Russia.
authors.forename: Denis S
authors.initials: DS
authors.lastname: Gruzdev
authors.affiliation: Winogradsky Institute of Microbiology, Research Center of Biotechnology, Russian Academy of Sciences, Moscow, Russia.
authors.forename: Pavel A
authors.initials: PA
authors.lastname: Sigalevich
authors.affiliation: Winogradsky Institute of Microbiology, Research Center of Biotechnology, Russian Academy of Sciences, Moscow, Russia.
authors.forename: Nikolay V
authors.initials: NV
authors.lastname: Pimenov
authors.affiliation: Institute of Bioengineering, Research Center of Biotechnology, Russian Academy of Sciences, Moscow, Russia.
authors.forename: Boris B
authors.initials: BB
authors.lastname: Kuznetsov
authors.affiliation: Winogradsky Institute of Microbiology, Research Center of Biotechnology, Russian Academy of Sciences, Moscow, Russia.
authors.forename: Vladimir M
authors.initials: VM
authors.lastname: Gorlenko
mesh_terms: D002244:Carbon / Q000378:metabolism*; D057486:Carbon Cycle; D002245:Carbon Dioxide / Q000032:analysis; D019414:Chlorobi / Q000378:metabolism; D017753:Ecosystem; D046448:Ice Cover; D007501:Iron / Q000737:chemistry*; D060106:Lakes / Q000737:chemistry / Q000382:microbiology*; D008697:Methane / Q000032:analysis; D010084:Oxidation-Reduction; D010100:Oxygen; D010788:Photosynthesis; D012426:Russia; D013440:Sulfides; D013455:Sulfur / Q000378:metabolism*; D014871:Water Microbiology
chemical_list: D013440:Sulfides; D002245:Carbon Dioxide; D013455:Sulfur; D002244:Carbon; D007501:Iron; D008697:Methane; D010100:Oxygen