Description of Ectothiorhodospira
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Moderately and extremely halophilic species, vibrioid or spirals, motile by bipolar flagella and have internal photosynthetic membranes as lamellar stacks. Growth is dependent on highly saline and alkaline conditions. In agar media, red- or green-colored colonies are formed. Photosynthetic pigments of the red-colored species are bacteriochlorophyll a and carotenoids of the normal spirilloxanthin series, with spirilloxanthin as the predominant component. The green-colored species, contain bacteriochlorophyll b the red species has bacteriochlorophyll a. The carotenoid content of Hlr. halochloris and Hlr. abdelmalekii is low. The carotenoid composition of both of these species is quite similar. Mainly methoxyrhodopin glucoside (major), rhodopin glucoside, and rhodopin have been found in Hlr. halochloris. First species to be described in this genus were Halorhodospira halophila, Halorhodospira halochloris and Halorhodospira abdelmalekii.