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A Microbial Biorealm page on the genus Thiocapsa

Thiocapsa roseopersicina. Imhoff, "The Chromataceae."


Higher order taxa:

Bacteria; Proteobactera; Gammaproteobacteria; Chromatiales; Chromatiaceae


Thiocapsa literalis, T. roseopersicina, T. purpurea

NCBI: Taxonomy Genome

Description and Significance

Thiocapsa are sulfur bacteria, meaning that they use reduce sulfur as an electron donor during photosynthesis. They are capable of oxidizing both sulfide and other reduced sulfur compounds. However, the growth of species can be inhbited by excessive amounts of these compounds. The amount of sulfur each organism requires varies from species to species. Thiocapsa are largely anaerobic.

Genome Structure

At present there is not yet an extensive body of research on the genome strucutre of Thiocapsa species.

Cell Structure and Metabolism

Thiocapsa litoralis. Photo by L.L. Mityushima.

Thiocapsa are nonmotile Gram-negative bacteria with a purple color. They have a spherical shape. Their photosynthetic equipment consists of two light-harvesting antennae complexes and a reaction center. They contain carotenoids which absorb light in addition to preventing photodamage, the main carotenoid being spirilloxanthin. The major light-harvesting pigment is bacteriochlorophyll a.

Thiocapsa are photosynthetic. Various species require different amounts of light in order to undergo this process, which determines their location in the water column. For example, Thiocapsa roseopersicina prefers high amounts of light, between 1,000 and 2,000 lux. However, Thiocapsa rosea grows at low intensities, usually between 50-300 lux.

Thiocapsa have a typical bacterial life cycle, reproducing by binary fission. They do not form spores.


Thiocapsa pendens. Imhoff, "The Chromitaceae."

Thiocapsa are found in aquatic environments, most often in fresh water. These include lakes, sulfur springs, and waste water ponds. The marine habitats include: shoreline sediments, lagoons, fjords, salt and soda lakes, sea ice, and the Black Sea. Their habitats have little or no oxygen. Under ideal conditions, Thiocapsa can form dense blooms.


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Herbert, Rodney A., Anthony Ranchou-Peyruse, Robert Duran, Rémy Guyoneaud, and Stephanie Schwabe. "Characterization of purple sulfur bacteria from the South Andros Black Hole cave system: highlights taxonomic problems for ecological studies among the genera Allochromatium and Thiocapsa." Environmental Microbiology. Volume 7 Issue 8 Page 1260 - August 2005.

Imhoff, Johannes F. "The Chromatiaceae." The Prokarytoes. Release 3.13. Accessed 26 July 2005.

Jones, Meriel. "Hot off the Press." Microbiology Today. August 2000;27:148-151.

Kovács, Ákos T, Gábor Rákhely, and Kornél L. Kovács. "Genes Involved in the Biosynthesis of Photosynthetic Pigments in the Purple Sulfur Photosynthetic Bacterium Thiocapsa roseopersicina." Appl Environ Microbiol. 2003 June; 69(6): 3093–3102.