Acidisphaera

Abstract

A.ci.di.sphae' ra . M.L. n. acidum an acid; M.L. fem. n. sphaera sphere; M.L. fem. n. Acidisphaera acid (‐requiring) coccoid microorganism. Proteobacteria / Alphaproteobacteria / Rhodospirillales / Acetobacteraceae / Acidisphaera Cells are cocci or coccobacilli , 0.7–0.9 × 0.9–1.6 µm. Nonmotile. Spore and capsules are not formed. Multiply by binary fission. Gram negative. Aerobic, having a strictly respiratory type of metabolism with oxygen as the terminal electron acceptor. Chemoorganotrophic. Produce bacteriochlorophyll a esterified with phytol and carotenoids as photosynthetic pigments only under aerobic growth conditions in the dark. Light stimulates aerobic growth and viability. Do not grow phototrophically under anoxic conditions in the light. Liquid cultures and colonies on agar media are pink or salmon‐pink. Growth occurs with a number of simple organic compounds as electron donor and carbon source. Growth on complex media containing peptone is poor. Sulfide, S 0 , thiosulfate, and Fe 2+ do not serve as electron donors for chemolithotrophic growth. Catalase and oxidase positive. Mesophilic. Obligately acidophilic , growing in the pH range of 3.5–6.0 (but not at pH 3.0 or 6.5). Freshwater bacteria that do not require NaCl for optimal growth. Ubiquinones with ten isoprene units (Q‐10) are present. Members of the class Alphaproteobacteria . Isolated from acidic mineral environments including surface water and sediment in acidic hot springs (at 42°C and below) and mine drainage streams. The mol % G + C of the DNA is : 69–70. Type species : Acidisphaera rubrifaciens Hiraishi, Matsuzawa, Kanbe and Wakao 2000b, 1545.