<Emphasis Type="Italic">Thiocapsa imhoffii</Emphasis>, sp. nov., an alkaliphilic purple sulfur bacterium of the family <Emphasis Type="Italic">Chromatiaceae</Emphasis> from Soap Lake,Washington (USA) |
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Authors: | Marie Asao Shinichi Takaichi Michael T Madigan |
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Institution: | (1) Department of Microbiology, Southern Illinois University, Carbondale, IL 62901-6508, USA;(2) Biological Laboratory, Nippon Medical School, 297 Kosugi-cho 2, Nakahara, Kawasaki 211-0063, Japan |
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Abstract: | An alkaliphilic purple sulfur bacterium, strain SC5, was isolated from Soap Lake, a soda lake located in east central Washington
state (USA). Cells of strain SC5 were gram-negative, non-motile, and non-gas vesiculate cocci, often observed in pairs or
tetrads. In the presence of sulfide, elemental sulfur was deposited internally. Liquid cultures were pink to rose red in color.
Cells contained bacteriochlorophyll a and spirilloxanthin as major photosynthetic pigments. Internal photosynthetic membranes were of the vesicular type. Optimal
growth of strain SC5 occurred in the absence of NaCl (range 0–4%), pH 8.5 (range pH 7.5–9.5), and 32°C. Photoheterotrophic
growth occurred in the presence of sulfide or thiosulfate with only a limited number of organic carbon sources. Growth factors
were not required, and cells could fix N2. Dark, microaerobic growth occurred in the presence of both an organic carbon source and thiosulfate. Sulfide and thiosulfate
served as electron donors for photoautotrophy, which required elevated levels of CO2. Phylogenetic analysis placed strain SC5 basal to the clade of the genus Thiocapsa in the family Chromatiaceae with a 96.7% sequence similarity to its closest relative, Thiocapsa
roseopersicina strain 1711T (DSM217T). The unique assemblage of physiological and phylogenetic properties of strain SC5 defines it as a new species of the genus
Thiocapsa, and we describe strain SC5 herein as Tca. imhoffii, sp. nov. |
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Keywords: | Anoxygenic phototrophic bacteria Purple sulfur bacteria Chromatiaceae Thiocapsa Alkaliphiles Extreme environments Soap Lake Soda lakes |
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