74 ORDER I. PSEUDOMONADALES 



FAMILY II. METHANOMONADACEAE BREED Fam. Nov.* 



(Oxydobacteriaceae Orla-Jensen, pro parte, Cent. f. Bakt., II Abt., 22, 1909, 329; 

 Protohacterieae Rahn, Cent. f. Bakt., II Abt., 96, 1937, 273.) 



Me. tha.no. mo. na.da'ce.ae. M.L. noun Methanonwnas, -adis a genus of bacteria; -aceae 

 ending to denote a familj^; M.L. fern. pi. n. Methanomonadaceae the Methanonwnas family. 



Rod -shaped organisms deriving their life energy from the oxidation of simple compounds 

 of hydrogen or carbon. Polar flagellate when motile. Gram-negative. Found in soil and 

 water. 



It is clear that the species placed in the genera in this family belong with other polar 

 flagellate bacteria (the group of pseudomonads in the broad sense). Their method of de- 

 riving energy from oxidative processes is in accord with that of many other polar-fiagellate 

 bacteria. As a matter of convenience and as a means of emphasizing the fact that the species 

 included here secure their energy from the oxidation of simple hydrogen and carbon com- 

 pounds, the genera that have been proposed to include these species are grouped into a 

 family separate from those of the species that secure their energy from the oxidation of 

 simple nitrogen or sulfur compounds on the one hand, and those that normally secure their 

 energy from the oxidation of glucose or other organic compounds on the other hand. Further 

 studies of the differences in physiology found among the polar flagellate bacteria are badly 

 needed. 



Key to the genera of the family Methanomonadaceae. 



I. Organisms deriving their life energy from the oxidation of simple compounds of hy- 

 drogen. 



A. Cells capable of securing growth energy by the oxidation of methane. 



Genus I. Methanomonas, p. 74. 



B. Cells capable of securing growth energy by the oxidation of hydrogen. 



Genus II. Hydrogenomonas , p. 75. 

 II. Organisms deriving their life energy from the oxidation of carbon monoxide. 



Genus III. Carhoxydomonas , p. 77. 



Genus I. Methanomonas Orla-Jensen, 1909. 

 (Cent. f. Bakt., II Abt., 22, 1909, 311.) 



Me.tha.no.mo'nas. Gr. methy wine; Gr. methe strong drink; M.L. methanum methane; 

 Gr. monas a unit, monad; M.L. fem.n. Methanomonas methane monad. 



Cells monotrichous, capable of obtaining energj' from oxidation of methane to CO2 

 and water. 



The type species is Methanomonas methanica (Sohngen) Orla-Jensen. 



1. Methanomonas methanica (Sohn- motile in young cultures by means of a 



gen, 1906) Orla-Jensen, 1909. {Bacillus single flagellum. In older cultures nearly 



me/AamciiS Sohngen, Cent. f. Bakt., II Abt., spherical. Can be cultivated in an atmos- 



15, 1906, 513; Orla-Jensen, Cent. f. Bakt., phere composed of one part CH4 and two 



II Abt., ^^, 1909, 311.) parts air on washed agar containing the 



me.tha'ni.ca. M.L. noun methanum necessary inorganic salts. The growth is 



methane; M.L. adj. melhanicus relating to membranous, 



methane. At the end of two weeks, the organisms 



Short rods, 0.5 to 0.8 by 2.0 to 3.0 microns, changed an atmosphere containing 225 ml 



* Revised })y Prof. Robert S. Breed, Cornell University, Geneva, New York, January, 

 1954. 



