Two halophilic Ectothiorhodospira strains with unusual morphological,physiological and biochemical characters |
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Authors: | Stefano Ventura Roberto De Philippis Riccardo Materassi Waldemaro Balloni |
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Affiliation: | (1) C.N.R. Centro di Studio dei Microorganismi/Microbiologia Autotrofi, Piazzale delle Cascine, 27, I-50144 Firenze, Italy;(2) Istituto di Agraria e Tecnica dell'Università, Piazzale delle Cascine, 27, I-50144 Firenze, Italy |
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Abstract: | Two strains belonging to the genus Ectothiorhodospira were isolated from enrichment cultures inoculated with sulfide-containing samples from the saltern of Trapani. Cells are motile short spirilla with internal stacks of membranes. During sulfide utilization they produce external globules of sulfur that are then completely oxidized to sulfate. These halophilic microorganisms need NaCl concentrations of 11% and 18% and a slightly alkaline pH. They are typical photoautotrophic bacteria, utilizing sulfide, sulfur and, only one of them, thiosulfate as photosynthetic electron donors; growth is stimulated by organic compounds. Neither of the two strains is capable of assimilatory sulfate reduction and neither grows in the dark. Pigments of the two strains are bacteriochlorophyll a and carotenoids of the normal spirilloxanthin series subgroup 1B. Quinones are Q8 and MK8 in a strain and Q8 and MK7 in the other one: the latter situation, with quinone side chains of different lengths, is atypical within phototrophic bacteria. For morphological, physiological and biochemical characters, at least one of these strains clearly stays apart from the six Ectothiorhodospira species described until now.List of abbreviations HPLC high performance liquid chromatography - TLC thin layer chromatography - Qn ubiquinone—number of isoprenoid units of the side chain - MKn menaquinone—number of isoprenoid units of the side chain - Rt retention time - Rf retention factorDedicated to the memory of Professor Gino Florenzano who inspired this work |
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Keywords: | Phototrophic bacteria Ectothiorhodo-spiraceae Halophilic bacteria Carotenoids Quinones Chemotype Taxonomy |
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