184 ORDER I. PSEUDOMONADALES 



Thesis, Leiden, 1898, 115 pp.. Delft, in Cent. f. Bakt., II Abt., 4, 1898, 857; Acetobader 

 Beijerinck, Proc. Kon. Akad. v. Wetenschapp., Amsterdam, 2, 1900, 503; Acetobacter Bei- 

 jerinck. Arch, n^erl. d. sciences exact, et natur., S^r. II, 6, 1901, 212; Acetobacter in Fuhr- 

 mann, Beiheft Bot. Centralbl., Orig., 19, 1905, 8; Acetimonas Orla-Jensen, Cent. f. Bakt., 

 II Abt., 22, 1909, 312; Acetobacter Winslow et al.. Jour. Bact., 5, 1920, 201; Acetomonas 

 Leifson, Antonie van Leeuwenhoek, 20, 1954, 109.) 



A.ce.to.bac'ter. L. noun acetum vinegar; M.L. mas.n. bacter the masculine form of the 

 Gr. neut.n. bactrum a rod or staff; M.L. mas.n. Acetobacter vinegar (acetic) rod. 



Individual cells ellipsoidal to rod-shaped, occurring singly, in pairs or in short or long 

 chains. Motile with polar flagella*, or non-motile. Involution forms may be spherical, 

 elongated, filamentous, club-shaped, swollen, curved or may even appear to be branched. 

 Young cells Gram-negative; old cells often Gram- variable. Obligate aerobes; as a rule 

 strongly catalase-positive, sometimes weakly so. Oxidize various organic compounds to 

 organic acids and other oxidation products which may undergo further oxidation. Com- 

 mon oxidation products include acetic acid from ethyl alcohol, gluconic and 5-keto- 

 gluconic acid from glucose, dihydroxy-acetone from glycerol, sorbose from sorbitol, etc. 

 Nutritional requirements vary from simple to complex. Development generally best in 

 yeast infusion or yeast autolysate media with added ethyl alcohol or other o.xidizable sub- 

 strates. Optimum temperature varies with the species. Widely distributed in nature where 

 they are particularly abundant in plant materials undergoing alcoholic fermentation; 

 of importance to man for their role in the completion of the carbon cycle and for the pro- 

 duction of vinegar. 



It is recognized that there are marked morphological and physiological similarities be- 

 tween species of Acetobacter and Pseudomonas (see Vaughn, Jour. Bact., 46, 1943, 394; and 

 Stanier, Jour. Bact., 54, 1947, 191, among others). However, the species of Acetobacter may 

 be differentiated from all other Pseudomonadaceae by their unique ability to oxidize sig- 

 nificant quantities of ethanol under the extremely acidic conditions imposed by the 

 presence of from about 2 to more than 11 per cent acetic acid. 



The evidence also indicates a significant difference in the end-products of hexose and di- 

 saccharide oxidation. The species of Acetobacter produce gluconic and 5-ketogluconic acids 

 from both glucose and maltose whereas species of Pseudomonas oxidize glucose to gluconic 

 and 2-ketogluconic acids and maltose to maltobionic acid (see Pervozvanski, Khim. Referat. 

 Zhur., 7, 1939, 43; Lockwood, Tabenkin and Ward, Jour. Bact., 4^, 1941, 51; Stodola and 

 Lockwood, Jour. Biol. Chem., 171, 1947, 213; Kluyver, Deley and Rijven, Antonie van 

 Leeuwenhoek, 16, 1950, 1; and Foda and Vaughn, Jour. Bact., 65, 1953, 233, among others). 



The type species is Acetobacter aceti (Beijerinck) Beijerinck. 



Key to the species of genus Acetobacter. 



I. Oxidize acetic acid to carbon dioxide and water. 



A. Utilizes ammonium salts as a sole source of nitrogen (Hoyer's solution). f 



1. Acetobacter aceti. 



* Leifson (Bact. Proc, 53rd Gen. Meeting Soc. Amer. Bact., 1953, 34, and Antonie van 

 Leeuwenhoek, 20, 1954, 102), in a study of the flagellation of cultures of Acetobacter, reports 

 that the species of Acetobacter that oxidize acetic acid are peritrichous, and that the species 

 that do not oxidize acetic acid ordinarily have four polar flagella. Further photographs such 

 as can be obtained with the electron microscope must, however, be obtained before the exact 

 point of attachment of the flagella can be determined with certaint3^ 



t It is not known with certainty whether Acetobacter pasteurianus and Acetobacter kuetz- 

 ingianus are capable of using inorganic nitrogen as a sole source of nitrogen for growth. 

 See Acetobacter rancens Beijerinck to which these two species are very closely related. Also 

 see Frateur, La Cellule, 53, 1950, 316^320. 



Species Nos. 2 to 3b inclusive will, however, utilize ammonium salts if supplied with 



