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AcidiphiliumRANK: GenusTAXONOMY: cellular organisms -> Bacteria -> Proteobacteria -> Alphaproteobacteria -> Rhodospirillales -> Acetobacteraceae -> Acidiphilium OVERVIEW: Cells are straight rods, 0.3–1.2 × 4.2 µm, multiply by binary fission and exhibit a pleomorphic tendency at varied pH values and in the presence of different carbon sources. Motile by means of polar, subpolar, and lateral flagella. Do not form spores or capsules. Gram negative. 16S rRNA structures and signatures conform to the Alphaproteobacteria. Cell suspensions and colonies are white to cream, yellow, pink, red, or brown. Strictly aerobic, chemoorganotrophic and chemolithotrophic bacteria containing photosynthetic pigments, categorized into the aerobic bacteriochlorophyll-containing bacteria. Main photosynthetic pigments are zinc-chelated bacteriochlorophyll (Zn-BChl) a and the carotenoid spirilloxanthin. Grow with simple organic compounds, such as sugars, as electron donors and carbon sources. Growth is inhibited in the presence of 0.6% yeast extract and low concentrations of acetate (0.25 mM) and lactate (2 mM). One species is a facultative chemolithotroph utilizing elemental sulfur as electron donor. Fe2+ does not serve as the electron donor for chemolithotrophic growth but has stimulatory effects on heterotrophic growth. Catalase is positive and oxidase negative or weakly positive. Mesophilic and obligately acidophilic bacteria growing in the pH range of 2.0–5.9 (but not at pH 6.1 and above). Straight-chain monounsaturated C18:1 acid is the major component of cellular fatty acids. Ubiquinones with ten isoprene (Q-10) units are present.The mol% G + C of the DNA is: 62.9–68.1.Type species: Acidiphilium cryptum |