202 COMMITTEE REPORT 



Cells rod-shaped, frequently in chains, non-motile. Cells 

 grow usually on the surface of alcoholic solutions as obligate 

 aerobes, securing growth energy by the oxidation of alcohol to 

 acetic acid. Also capable of utilizing certain other carbonace- 

 ous compounds, as sugar and acetic acid. Elongated, filamentous, 

 club-shaped, swollen and even branched cells may occur as invo- 

 lution forms. 



The type species is Acetobacter aceti (Thomson 1852), Com- 

 mittee. 



Genus 5. N itrosomonas Winogradsky 1892a, p. 127 



Includes N itrosococcus Winogradsky 1892 



Cells rod-shaped or spherical, motile or non-motile, if motile 

 with polar flagella. Capable of securing growth energy by the 

 oxidation of ammonia to nitrites. Growth on media containing 

 organic substances scanty or absent. 



The type species is N itrosomonas europoea Winogradsky. 



Genus 6. Nitrobacter Winogradsky 1892b, p. 87 

 Synonym: Nitrosobacterium? Rullmann 1897. 



Cells rod-shaped, non-motile, not growing readily on organic 

 media or in the presence of ammonia. Cells capable of securing 

 growth energy by the oxidation of nitrites to nitrates. 



The type species is Nitrobacter Winogradskyi, Committee 

 1917a, p. 552. 



Tribe 2. Azotobactereae 



Nitrogen-fixing organisms 



Genus 7. Azotobacter Beijerinck 1901a, p. 561 



Synonyms: Parachromatium Beijerinck 1903; Azotomonas Jensen 

 1909. 



Relatively large rods, or even cocci, sometimes almost yeast- 

 like in appearance, dependent primarily for growth energy upon 

 the oxidation of carbohydrates. Motile or non-motile; when 



