Page:Bergey's manual of determinative bacteriology.djvu/90

 FAMILY I. NITROBACTERACEAE BUCHANAN, 1917.

Ni.tro.bac.te.ra′ce.ae. M.L. Nitrobacter name of type genus of the family; -aceae ending to denote a family; M.L. plural noun Nitrobacteraceae the Nitrobacter family.

Cells without endospores; rod-shaped, ellipsoidal or even spherical (Nitrosococcus) or spirillar in shape (Nitrosospira). Flagella polar, occasionally absent. Gram-negative. Organisms which derive energy from the oxidation of ammonia to nitrite or from the oxidation of nitrite to nitrate; these bacteria depend on this oxidation for growth and fail to grow on media containing organic matter in the absence of the specific inorganic materials used as sources of energy. Many organic compounds commonly used in standard culture media are toxic to these bacteria. Not parasitic. Commonly found in soil and fresh water.

The type genus for the family is Nitrobacter Winogradsky.

As it appears to be a more logical arrangement, the genera that include the species that oxidize ammonia are discussed first although the type genus does not belong in this group.

I. Ammonia oxidized to nitrite.


 * A. Zoogloeae not formed. Cells occur separately, free or in dense aggregates.


 * 1. Cells not spiral-shaped.


 * a. Cells ellipsoidal.


 * aa. Cells spherical.


 * 2. Cells spiral.


 * B. Zoogloeae formed.


 * 1. Zoogloea surrounded by a common membrane forming a cyst.


 * 2. No common membrane surrounds the cells. The massed cells are embedded in slime.

II. Nitrite oxidized to nitrate.


 * A. Zoogloeae not formed.


 * B. Zoogloeae formed.

(Nitromonas Winogradsky, Ann. Inst. Past., 4, 1890, 257; not Nitromonas Orla-Jensen, Cent. f. Bakt., II Abt., 22, 1909, 334; Arch. Sci. biol., St. Petersburg, 1, 1892, 127; emend. S. and H. Winogradsky, Ann. Inst. Past., 50, 1933, 393.)

Ni.tro.so.mo′nas. M.L. nitrosus nitrous; Gr. monas, monadis a unit, monad; M.L. fem. n. Nitrosomonas nitrous monad, i.e., the monad producing nitrite. Cells ellipsoidal, non-motile or with a single polar flagellum, occurring singly, in pairs, short chains or irregular masses which are not enclosed in a common membrane. Oxidize ammonia to nitrite more rapidly than the other genera of this family.

The type species is Nitrosomonas europaea Winogradsky.