Alkalispirillum mobile gen. nov., spec. nov., an alkaliphilic non-phototrophic member of the Ectothiorhodospiraceae

From cultures of the anoxygenic phototroph Halorhodospira halophila SL-1, a n aerobic, gram-negative spirillum was isolated. This moderately halophilic , alkaliphilic bacterium was motile by means of a single polar flagellum. I t is described here as Alkalispirillum mobile gen. nov., spec. nov. Phyloge netic analysis of the Alkalispirillum mobile 16S rRNA gene led to its class ification in the gamma -subclass of the Proteobacteria, as it appears close ly related to phototrophic purple sulfur bacteria of the genera Ectothiorho dospira and Halorhodospira. Surprisingly, A. mobile is an obligate aerobe. The organism grows optimally with a number of carboxylic acids (such as sod ium acetate) as carbon source, at 2% (i.e. approximately 0.34 M) sodium chl oride, at pH 9-10, and at temperatures ranging from 35 to 38 degreesC. The dominant cellular fatty acids of Alkalispirillum mobile are C-12:0, C-16:0, C-18:1cis11, and C-18:0; its G+C content is 66.2+/-0.5 mol%.