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MANUAL OF DETERMINATIVE BACTERIOLOGY 



p. 422). In 1940, he discovered that the second species produced spores. In a per- 

 sonal communication (March 20, 1945) he suggests that further work is needed before 

 the relationships of these organisms can be clarified. 



Genus A. Methanobacterium Kluyver and Van Niel. 

 (Cent. f. Bakt., II Abt., 94, 1936, 399.) 

 Straight or slightly bent rods, sometimes united in bundles or long chains. Usu- 

 ally non-motile. Endospores sometimes formed. Anaerobic. Chemo-heterotro- 

 phic or chemo-autotrophic oxidizing various organic or inorganic compounds and 

 reducing carbon dioxide to methane. Gram- variable, usually negative. 

 The type species is Methanobacterium soehngenii Barker. 



1. Methanobacteriimi soehngenii Bar- 

 ker. (Methane bacterium, Sohngen, Dis- 

 sertation, Delft, 1906; Barker, Arch. f. 

 Mikrobiol., 7, 1936, 433.) Named for 

 Prof. X. L. Sohngen who first studied 

 this organism. 



Rods : Straight to slightly bent, moder- 

 ately long. Non-motile. Non-spore- 

 forming. Gram-negative. 



In liquid cultures cells are character- 

 istically joined into long chains which 

 often lie parallel to one another so as to 

 form bundles. 



Acetate and n-butyrate but not pro- 

 pionate are fermented with the produc- 

 tion of methane and carbon dioxide. 



Ethjd and n-butyl alcohols not fer- 

 mented . 



Obligate anaerobe. 



Source: Enrichment cultures contain- 

 ing acetate or butyrate as the only 

 organic compound. Four strains were 

 isolated from acetate enrichment cul- 

 tures. The cultures were highly purified 

 but not strictly pure. 



Habitat: Canal mud, sewage. Prob- 

 ably occurs widely in fresh water sedi- 

 ments where anaerobic conditions pre- 

 vail. 



2. Methanobacteritun omelianskii Bar- 

 ker. (Bacille de la decomposition m6- 

 thanique de I'alcohol ethylique, 

 Omeliansky, Ann. Inst. Past., 30, 1916, 

 80; Barker, Arch f. Mikrobiol., 7, 1936, 

 436; also see Barker, Antonie van Leeu- 

 wenhoek, 6, 1940, 201 and Jour. Biol. 

 Chem., 137, 1941, 153.) Named for 

 Prof. W. Omeliansky who first observed 

 the organism. 



Rods: 0.6 to 0.7 by 1.5 to 10 microns, 

 usual length 3 to 6 microns, unbranched, 

 straight or slightly bent. Usually non- 

 motile, occasionally feeble motility is 

 observed. Spores of low heat resistance 

 formed, spherical, terminal, swelling the 

 rods. 



Primary alcohols, including ethyl, 

 propyl, n-butyl and n-amyl alcohols, are 

 oxidized to the corresponding fatty 

 acids. Secondary alcohols, including 

 isopropyl and sec-butyl, are oxidized to 

 the corresponding ketones. Hydrogen 

 is oxidized. 



Fatty and hydro.xy acids, glucose, 

 polyalcohols and amino acids are not 

 attacked. 



Carbon dioxide is used and converted 

 to methane. Growth and alcohol oxida- 

 tion are directly proportional to the 

 carbon dioxide supply at low concen- 

 trations. 



Nitrate, sulfate and oxygen cannot be 

 used as oxidizing agents. 



Utilizes ethyl alcohol best of all or- 

 ganic compounds. 



Utilizes ammonia as a nitrogen source. 



Growing range: pH 6.5 to 8.1. 



Optimum temperature 37° to 40°C. 

 Maximum 46° to 48°C. 



Obligate anaerobe. 



Source: Soil, fresh water and marine 

 muds, rabbit feces, sewage. Pure cul- 

 tures were isolated from fresh water and 

 marine muds (Barker, loc. cit., 1940). 



Habitat: Wherever organic matter is 

 decomposing in an anaerobic, approxi- 

 mately neutral environment. 



