Salinity responses of benthic microbial communities in a solar saltern (Eilat, Israel).
The salinity responses of cyanobacteria, anoxygenic phototrophs, sulfate reducers, and methanogens from the laminated endoevaporitic community in the solar salterns of Eilat, Israel, were studied in situ with oxygen microelectrodes and in the laboratory in slurries. The optimum salinity for the sulfate reduction rate in sediment slurries was between 100 and 120 per thousand, and sulfate reduction was strongly inhibited at an in situ salinity of 215 per thousand. Nevertheless, sulfate reduction was an important respiratory process in the crust, and reoxidation of formed sulfide accounted for a major part of the oxygen budget. Methanogens were well adapted to the in situ salinity but contributed little to the anaerobic mineralization in the crust. In slurries with a salinity of 180 per thousand or less, methanogens were inhibited by increased activity of sulfate-reducing bacteria. Unicellular and filamentous cyanobacteria metabolized at near-optimum rates at the in situ salinity, whereas the optimum salinity for anoxygenic phototrophs was between 100 and 120 per thousand.
Danish Center for Earth System Science, Institute of Biology, University of Southern Denmark, University of Odense, Odense, Denmark. ketilsorensen@unc.edu
Ketil Bernt
KB
Sørensen
Donald E
DE
Canfield
Aharon
A
Oren
D000458:Cyanobacteria / Q000302:isolation & purification / Q000378:metabolism; D017753:Ecosystem; D004783:Environmental Microbiology; D007557:Israel; D008697:Methane / Q000032:analysis; D017019:Methanosarcinaceae / Q000302:isolation & purification / Q000378:metabolism; D010084:Oxidation-Reduction; D010100:Oxygen / Q000032:analysis; D010101:Oxygen Consumption; D010788:Photosynthesis; D012965:Sodium Chloride / Q000032:analysis; D013431:Sulfates / Q000032:analysis; D013440:Sulfides / Q000032:analysis
D013431:Sulfates; D013440:Sulfides; D012965:Sodium Chloride; D008697:Methane; D010100:Oxygen