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GallionellaRANK: GenusTAXONOMY: cellular organisms -> Bacteria -> Proteobacteria -> Betaproteobacteria -> Gallionellales -> Gallionellaceae -> Gallionella OVERVIEW: Gram-negative, bean-shaped cells, usually 0.5–0.8 × 1.6–2.5 µm, that secrete an extracellular twisted stalk from the concave side, 0.3–0.5 µm in width and up to 400 µm or more in length. The stalk is composed of numerous 2 nm-wide fibers and is produced under microaerophilic conditions when cells are in late exponential or stationary growth phase. Motile by means of a polar flagellum. Microaerophilic; chemolithotrophic growth can be obtained in vitro using oxygen and ferrous iron concentration gradients in a salt medium with CO2 as sole carbon source (Table BXII.β.108). Mixotrophic metabolism has been demonstrated with glucose, fructose, and sucrose. Can be found where anaerobic groundwater with ferrous iron reaches an oxygen-containing environment. Belongs to the Betaproteobacteria, family Gallionellaceae, with one known species, G. ferruginea. Most closely related species according to 16S rDNA sequence analysis is the chemolithotroph Nitrosospira multiformis, distantly related with a 16S rDNA sequence similarity of 90%.The mol% G + C of the DNA is: 51–54.6 (Hanert, 1989). Type species: Gallionella ferruginea |