RANK: Genus

TAXONOMY: cellular organisms -> Bacteria -> Proteobacteria -> Betaproteobacteria -> Nitrosomonadales -> Nitrosomonadaceae -> Nitrosomonas


Spherical, ellipsoidal, or rod-shaped cells (Figures 1–3, and 4). Strains belonging to the same species are generally very similar in the shape and size of their cells. Cells occur singly or occasionally in short chains. Depending on the growth conditions, cells are free-living or embedded in slimy aggregates. Gram-negative cell wall, but some marine representatives show an additional outer cell-wall layer composed of subunits arranged in a macromolecular array (Watson and Remsen, 1969). Motile cells possess polar flagella. Intracytoplasmic membranes are arranged as flattened vesicles, primarily in the peripheral cytoplasm (Figures 1–3, and 4). Carboxysomes (Figure 5) are present in some species. Urea can be used as ammonia source by many, but not all, species. The Ks values for oxidation of NH3 range between 0.6 and 158 μM. Most, if not all, species are predominantly or exclusively present in special environments.The mol% G + C of the DNA is: 45–54 (Tm).Type species: Nitrosomonas europaea