A gas vesiculate planktonic strain of the purple non-sulfur bacterium Rhodoferax antarcticus isolated from Lake Fryxell, Dry Valleys, Antarctica |
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Authors: | Deborah O. Jung Laurie A. Achenbach Elizabeth A. Karr Shinichi Takaichi Michael T. Madigan |
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Affiliation: | (1) Department of Microbiology, Southern Illinois University, Carbondale, IL 62901-6508, USA;(2) Present address: Department of Microbiology, Ohio State University, 484 West 12th Avenue, Columbus, OH 43210, USA;(3) Biological Laboratory, Nippon Medical School, 297 Kosugi-cho 2, Nakahara, Kawasaki, 211-0063, Japan |
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Abstract: | A moderately psychrophilic purple non-sulfur bacterium, Rhodoferax antarcticus strain Fryx1, is described. Strain Fryx1 was isolated from the water column under the ice of the permanently frozen Lake Fryxell, Antarctica. Cells of Fryx1 are long thin rods and contain gas vesicles, the first report of such structures in purple non-sulfur bacteria. Gas vesicles are clustered at 2–4 sites per cell. Surprisingly, the 16S rRNA gene sequence of strain Fryx1 is nearly identical to that of Rfx. antarcticus strain AB, a short, vibrio-shaped phototroph isolated from an Antarctic microbial mat. Although showing physiological parallels, strains AB and Fryx1 differ distinctly in their morphology and absorption spectra. DNA–DNA hybridization shows that the genomes of strains AB and Fryx1 are highly related, yet distinct. We conclude that although strains AB and Fryx1 may indeed be the same species, their ecologies are quite different. Unlike strain AB, strain Fryx1 has adapted to a planktonic existence in the nearly freezing water column of Lake Fryxell.Dedicated to Prof. Dr. Hans Günter Schlegel on the occasion of his 80th birthday. |
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Keywords: | Purple anoxygenic phototrophic bacteria Lake Fryxell Antarctica Rhodoferax antarcticus Gas vesicles Psychrophily |
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