1. Nitrosomonas europaea Winogradsky, 1892. (Arch. Sci. biol., St. Petersburg, 1, 1892, 127.)
eu.ro.pae′a. Gr. adj. europaeus of Europe, European.
Rods, 0.9 to 1.0 by 1.1 to 1.8 microns, occurring singly, rarely in chains of three to four. Possess a single polar flagellum 3 to 4 times the length of the rods, or rarely one at either end.
Grow readily in aqueous media without organic matter and containing ammonium sulfate, potassium phosphate and magnesium carbonate. The cells accumulate in soft masses around the particles of magnesium carbonate at the bottom of the flask. The liquid is occasionally turbid through development of motile swarm cells or monads.
Small, compact, sharply defined colonies brownish in color on silica gel.
Aerobic.
Strictly autotrophic.
Source: Soils of Zurich, Switzerland; of Gennevilliers, France; and Kazan, Russia.
Habitat: Presumably widely distributed in soil.
2. Nitrosomonas monocella Nelson, 1931. (Zent. f. Bakt., II Abt., 83, 1931, 287.)
mon.o.cel′la. Gr. monus single; L. cella oom, cell; M.L. adj. monocellus one-celled.
Ovoid rods, 0.6 to 0.9 micron, often occurring in pairs. Young cells nearly spherical. Motile by means of a single polar flagellum 3 to 5 times as long as the rod. Gram-positive (Nelson). Found negative by H. J. Conn (personal communication).
No growth in nutrient broth, nutrient agar, nutrient or plain gelatin, plain or litmus milk, glucose or plain yeast water, or on potato.
Silica gel or agar plates of inorganic medium: No typical colonies, but yellowish brown masses of growth around particles of CaCO2 in the medium.
Inorganic liquid medium containing ammonium salts: Uniform development throughout the liquid as well as in the carbonate sediment.
Even low concentrations of organic matter retard or completely inhibit the initiation of growth. Plant extracts are toxic.
Free CO2 and O2 necessary for growth.
Optimum pH, 8.0 to 9.0. Poor growth below pH 7.0. Some growth above pH 9.0.
Optimum temperature for growth and oxidation, 28° C.
Aerobic.
Strictly autotrophic.
Source: Isolated from field soil.
Habitat: Presumably widely distributed in soil.
Genus II. Nitrosococcus Winogradsky, 1892.
(Arch. Sci. biol., St. Petersburg, 1, 1892, 127.)
Ni.tro.so.coc′cus. M.L. nitrosus nitrous; Gr. coccus grain, berry; M.L. mas. n. Nitrosococcus nitrous sphere.
Cells large spheres, non-motile, not producing zoogloeae. Oxidize ammonia to nitrite.
The type species is Nitrosococcus nitrosus (Migula) Buchanan.
1. Nitrosococcus nitrosus (Migula, 1900) Buchanan, 1925. (Nitrosococcus Winogradsky, Ann. Inst. Past., 5, 1891, 577; Arch. Sci. biol., St. Petersburg, 1, 1892, 127; Micrococcus nitrosus Migula. Syst. d. Bakt., 2, 1900, 194; Buchanan, Gen. Syst. Bact., 1925, 402.)
ni.tro′sus. M.L. adj. nitrosus nitrous.
Large spheres, 1.5 to 1.7 microns in size, with thick cell membranes. Motility could not be demonstrated. Stain readily with aniline dyes. Zoogloea formation not observed. Gram-positive (Omelianski, Cent. f. Bakt., II Abt., 19, 1907, 263).
Liquid medium: Turbid.
Silica gel: Both dark and light colonies. Surface colonies look like small drops of a turbid yellowish liquid.
Aerobic.
Optimum temperature, between 20° and 25° C.
Source: Isolated from soil from Quito,
