Abstract

Large Sulfur Bacteria of the Family Beggiatoaceae are found world wide in or on top of aquatic sediments, which contain sulphide. In environments with high sulphide fluxes, such as coastal sediments especially in upwelling areas, hydrothermal vents, seeps or whale falls, they may build up enormous biomasses and giant species with cell diameters of several 100 µm are frequently encountered. They live by the oxidation of sulphide with oxygen or nitrate. The latter can be accumulated in extremely high concentrations within a central vacuole. Apart from the obvious influence of these bacteria on the sulphur and nitrogen cycling in sulphidic sediments, they have also been found to accumulate phosphorus, which they release periodically leading to a rapid formation of apatite.