Genus Xviii Thiohalocapsa Imhoff Suling and Petri 1998b 1139VP

Johannes F. Imhoff and Pierre Caumette

Thi'o.ha.lo.cap'sa. Gr. n. thios sulfur; Gr. gen. n. halos of the salt; L. fem. n. capsa capsule; M.L. fem. n. Thiohalocapsa the sulfur capsule of the salt.

Cells spherical, nonmotile, multiply by binary fission. Individual cells surrounded by a strong slime capsule and cell aggregates formed. Gram negative, belong to the Gammaproteobacteria, and contain internal photosynthetic membranes of vesicular type with bacteriochlorophyll a and carotenoids as photosynthetic pigments.

Photolithoautotrophic growth under anoxic conditions in the light with sulfide, S0, and possibly other electron donors. During oxidation of sulfide, S0 transiently stored inside the cells in the form of highly refractile globules. Final oxidation product is sulfate. In the presence of sulfide and bicarbonate, simple organic substrates are photoassimilated. Chemolithotrophic or chemo-organotrophic growth is possible under microoxic to oxic conditions in the dark.

Mesophilic bacteria with optimum growth at 20-30°C and pH 6.5-7.5. Elevated concentrations of sodium chloride required for growth.

Habitat: Sulfide-containing waters and sediments of saltern and other coastal habitats with elevated salt concentrations and exposed to the light.

Type species: Thiohalocapsa halophila (Caumette, Baulaigue and Matheron 1991) Imhoff, Suling and Petri 1998b, 1139 (Thi-ocapsa halophila Caumette, Baulaigue and Matheron 1991, 175.)

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