title: Comparative proteomics and activity of a green sulfur bacterium through the water column of Lake Cadagno, Switzerland.
abstract: Primary production in the meromictic Lake Cadagno, Switzerland, is dominated by anoxygenic photosynthesis. The green sulfur bacterium Chlorobium clathratiforme is the dominant phototrophic organism in the lake, comprising more than half of the bacterial population, and its biomass increases 3.8-fold over the summer. Cells from four positions in the water column were used for comparative analysis of the Chl. clathratiforme proteome in order to investigate changes in protein composition in response to the chemical and physical gradient in their environment, with special focus on how the bacteria survive in the dark. Although metagenomic data are not available for Lake Cadagno, proteome analysis was possible based on the completely sequenced genome of an isolated strain of Chl. clathratiforme. Using LC-MS/MS we identified 1321 Chl. clathratiforme proteins in Lake Cadagno and quantitatively compared 621 of these in the four samples. Our results showed that compared with cells obtained from the photic zone, cells collected from the dark part of the water column had the same expression level of key enzymes involved in carbon metabolism and photosynthetic light harvesting. However, most proteins participating in nitrogen and sulfur metabolism were twofold less abundant in the dark. From the proteome analysis we were able to show that Chl. clathratiforme in the photic zone contains enzymes for fixation of N(2) and the complete oxidation of sulfide to sulfate while these processes are probably not active in the dark. Instead we propose that Chl. clathratiforme cells in the dark part of the water column obtain energy for maintenance from the fermentation of polyglucose. Based on the observed protein compositions we have constructed possible pathways for C, N and S metabolism in Chl. clathratiforme.
authors: Department of Biology and Nordic Center for Earth EvolutionDepartment of Biochemistry and Molecular Biology, University of Southern Denmark, DK-5230 Odense M, Denmark.Department of Biology, University of Copenhagen, DK-2200 Copenhagen N, Denmark.Cantonal Institute of Microbiology, CH-6500 Bellinzona and Microbial Ecology and Microbiology Unit, Plant Biology Department, University of Geneva, CH-1211 Geneva, Switzerland.Alpine Biology Center Foundation Piora, Quinto, Switzerland.
authors: Kirsten S
authors: KS
authors: Habicht
authors: Department of Biology and Nordic Center for Earth EvolutionDepartment of Biochemistry and Molecular Biology, University of Southern Denmark, DK-5230 Odense M, Denmark.Department of Biology, University of Copenhagen, DK-2200 Copenhagen N, Denmark.Cantonal Institute of Microbiology, CH-6500 Bellinzona and Microbial Ecology and Microbiology Unit, Plant Biology Department, University of Geneva, CH-1211 Geneva, Switzerland.Alpine Biology Center Foundation Piora, Quinto, Switzerland.
authors: Mette
authors: M
authors: Miller
authors: Department of Biology and Nordic Center for Earth EvolutionDepartment of Biochemistry and Molecular Biology, University of Southern Denmark, DK-5230 Odense M, Denmark.Department of Biology, University of Copenhagen, DK-2200 Copenhagen N, Denmark.Cantonal Institute of Microbiology, CH-6500 Bellinzona and Microbial Ecology and Microbiology Unit, Plant Biology Department, University of Geneva, CH-1211 Geneva, Switzerland.Alpine Biology Center Foundation Piora, Quinto, Switzerland.
authors: Raymond P
authors: RP
authors: Cox
authors: Department of Biology and Nordic Center for Earth EvolutionDepartment of Biochemistry and Molecular Biology, University of Southern Denmark, DK-5230 Odense M, Denmark.Department of Biology, University of Copenhagen, DK-2200 Copenhagen N, Denmark.Cantonal Institute of Microbiology, CH-6500 Bellinzona and Microbial Ecology and Microbiology Unit, Plant Biology Department, University of Geneva, CH-1211 Geneva, Switzerland.Alpine Biology Center Foundation Piora, Quinto, Switzerland.
authors: Niels-Ulrik
authors: NU
authors: Frigaard
authors: Department of Biology and Nordic Center for Earth EvolutionDepartment of Biochemistry and Molecular Biology, University of Southern Denmark, DK-5230 Odense M, Denmark.Department of Biology, University of Copenhagen, DK-2200 Copenhagen N, Denmark.Cantonal Institute of Microbiology, CH-6500 Bellinzona and Microbial Ecology and Microbiology Unit, Plant Biology Department, University of Geneva, CH-1211 Geneva, Switzerland.Alpine Biology Center Foundation Piora, Quinto, Switzerland.
authors: Mauro
authors: M
authors: Tonolla
authors: Department of Biology and Nordic Center for Earth EvolutionDepartment of Biochemistry and Molecular Biology, University of Southern Denmark, DK-5230 Odense M, Denmark.Department of Biology, University of Copenhagen, DK-2200 Copenhagen N, Denmark.Cantonal Institute of Microbiology, CH-6500 Bellinzona and Microbial Ecology and Microbiology Unit, Plant Biology Department, University of Geneva, CH-1211 Geneva, Switzerland.Alpine Biology Center Foundation Piora, Quinto, Switzerland.
authors: Sandro
authors: S
authors: Peduzzi
authors: Department of Biology and Nordic Center for Earth EvolutionDepartment of Biochemistry and Molecular Biology, University of Southern Denmark, DK-5230 Odense M, Denmark.Department of Biology, University of Copenhagen, DK-2200 Copenhagen N, Denmark.Cantonal Institute of Microbiology, CH-6500 Bellinzona and Microbial Ecology and Microbiology Unit, Plant Biology Department, University of Geneva, CH-1211 Geneva, Switzerland.Alpine Biology Center Foundation Piora, Quinto, Switzerland.
authors: Lasse G
authors: LG
authors: Falkenby
authors: Department of Biology and Nordic Center for Earth EvolutionDepartment of Biochemistry and Molecular Biology, University of Southern Denmark, DK-5230 Odense M, Denmark.Department of Biology, University of Copenhagen, DK-2200 Copenhagen N, Denmark.Cantonal Institute of Microbiology, CH-6500 Bellinzona and Microbial Ecology and Microbiology Unit, Plant Biology Department, University of Geneva, CH-1211 Geneva, Switzerland.Alpine Biology Center Foundation Piora, Quinto, Switzerland.
authors: Jens S
authors: JS
authors: Andersen
mesh_terms: D018533:Biomass; D002244:Carbon / Q000378:metabolism; D002245:Carbon Dioxide / Q000378:metabolism; D041883:Chlorobium / Q000302:isolation & purification / Q000378:metabolism*; D005618:Fresh Water / Q000737:chemistry / Q000382:microbiology; D009584:Nitrogen / Q000378:metabolism; D010788:Photosynthesis; D020543:Proteome / Q000378:metabolism*; D012621:Seasons; D013431:Sulfates / Q000378:metabolism; D013557:Switzerland; D014871:Water Microbiology
chemical_list: D020543:Proteome; D013431:Sulfates; D002245:Carbon Dioxide; D002244:Carbon; D009584:Nitrogen