Beggiatoa (beg-ee-a-toe-a) is a colourless sulphur bacterium which occurs as filaments of various widths. Beggiatoa is found in sediments above the reduced zone. It oxidizes hydrogen sulphide, producing elemental sulphur which is deposited within the bacterial cell as sulphur granules visible inside this filament . May be very long. These cells can glide, a good trait for organisms which live in a habitat the characteristics of which are changing depending on whether there is or is not overlying water or if or if not there is sunlight. They don t usually make these cute spirals. Differential interference contrast. This picture was taken by David Patterson, Linda Amaral Zettler and Virginia Edgcomb of material from the salt marsh at Little Sippewissett (Massachusetts, USA) in Autumn, 2000 and in Spring and summer, 2001. Image copyright: D. J. Patterson, L. Amaral-Zettler and V. Edgcomb, image used under license to MBL (micro*scope).
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From the collection
Little Sippewissett salt marsh, Massachusetts, USA
|Description of Beggiatoa: Filamentous sulfur-oxidizing bacteria, including some of the largest and most conspicuous bacteria in nature. White or yellow color, wide and long filaments, and may form aggregates or mats such that they can be easily seen on surfaces by the naked eye. Oxidize sulfide to elemental sulfur that is stored as intracellular sulfur globules, which give the cells their white or yellow colour. The metabolic spectrum includes obligate autotrophy with sulfide and other reduced sulfur compounds as energy source, to strict heterotrophy based on organic carbon and energy sources. Biogenic or geothermal sulfide is oxidized to elemental sulfur, and subsequently in autotrophic strains to sulfate, to provide energy and reducing power for CO2 fixation and biomass synthesis. The electron acceptor for sulfide oxidation is oxygen or nitrate . The requirement for oxygen and sulfide, two mutually highly reactive chemical species, limits Beggiatoa to sites where there is a several oxygen discontinuity profile (i.e. where oxic conditions meet anoxic conditions) Distinguished from Thioploca because filaments are not enclosed in a gelatinous sheath. |