Taxonomic Comments

Thiohalocapsa halophila was originally described as a Thiocapsa species (Caumette et al., 1991), because its phenotypic properties were in agreement with this genus classification, according to Pfennig and Traper (1989). Cells are spherical and nonmotile purple sulfur bacteria. Because phylogenetic relationships and salt response clearly distinguish Thiohalocapsa halophila from species of the genus Thiocapsa (Guyoneaud et al., 1998b; Imhoff et al., 1998b), this bacterium was transferred to the new genus Thiohalocapsa (Imhoff et al., 1998b).

Further Reading

Guyoneaud, R., Suling,J., Petri, R., Matheron, R., Caumette, P., Pfennig, N. and Imhoff, J.F. 1998. Taxonomic rearrangements of the genera Thiocapsa and Amoebobacteron the basis of 16S rDNA sequence analyses and description of Thiolamprovum gen. nov. Int. J. Syst. Bacteriol. 48: 957-964.

Caumette, P., Baulaigue, R. and Matheron, R. 1991. Thiocapsa halophila, sp. nov., a new halophilic phototrophic purple sulfur bacterium. Arch. Microbiol. 155: 170-176. Imhoff, J.F., Suling, J. and Petri, R. 1998. Phylogenetic relationships among the Chromatiaceae, their taxonomic reclassification and description of the new genera Allochromatium, Halochromatium, Isochro-matium, Marichromatium, Thiococcus, Thiohalocapsa and Thermochroma-tium. Int. J. Syst. Bacteriol. 48: 1129-1143.

List of species of the genus Thiohalocapsa

1. Thiohalocapsa halophila (Caumette, Baulaigue and Matheron 1991) Imhoff, Suling and Petri 1998b, 1139VP (Thiocapsa halophila Caumette, Baulaigue and Matheron 1991, 175.)

ha.lo' Gr. n. hals salt; Gr. adj. philos loving; M.L. fem. adj. halophila salt-loving.

Cells spherical, 1.5-2.5 |im in diameter, form aggregates of 2, 4, or more cells, nonmotile. Color of cell suspensions purple-red. Photosynthetic pigments are bacteriochlorophyll a and okenone.

Photolithoautotrophic growth occurs with hydrogen, sulfide, S0, sulfite, and thiosulfate as electron donors. In presence of sulfide and bicarbonate, acetate, pyruvate, lactate, and fructose are photoassimilated. Glycerol and glucose poorly used. Chemolithotrophic or chemoorganotrophic growth is possible under microoxic conditions in the dark. Assimilatory sulfate reduction is absent. Vitamin B12 required.

Mesophilic and halophilic bacterium with optimum growth at 20-30°C, pH 7.0 (pH range 6.0-8.0), and at 48% NaCl (salinity range 3-20% NaCl).

Habitat: Reduced sediments in coastal saltern with salt deposits exposed to light.

The mol% G + C of the DNA is: 65.9-66.6 (Tm). Type strain: SG3202, ATCC 49740, DSM 6210. GenBank accession number (16S rRNA): AJ002796.

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