180 MANUAL OF DETERMINATIVE BACTERIOLOGY 



terium Ludwig, in abstract of Hoyer's Inaug. Diss., Cent. f. Bakt., II Abt., 4, 1898, 

 867; Acetimonas Orla-Jensen, Cent. f. Bakt., II Abt., 22, 1909, 312. 



In addition, the sub-generic names E uacetobacter and Acetogluconobacier have 

 been proposed by Asai, Jour. Agr. Soc. Japan, 11, 1935, 502. Tlie genus Gluconobacter 

 and the sub-genera Eugluconobacter and Gluconoacetobacter Asai {loc. cit.) may be 

 synonyms in whole or in part. 



Individual cells ellipsoidal to long and 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 even 

 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. Common oxidation products include acetic acid from ethyl alcohol, 

 gluconic and sometimes ketogluconic acid from glucose, dihydroxyacetone from gly- 

 cerol, sorbose from sorbitol, etc. Nutritional requirements vary from simple to com- 

 plex. Development generally best in yeast infusion or yeast autolysate media with 

 added ethyl alcohol or other oxidizable substrate. Optimum temperature variable 

 with the species. Widely distributed in nature where they are particularly abun- 

 dant in plant materials undergoing alcoholic fermentation; of importance to man for 

 their role in the completion of the carbon cycle and for the production of vinegar. 



The type species is Acetobacter aceti (Kiitzing) Beijerinck. 



Key to species of genus Acetobacter. 

 I. Oxidize acetic acid to carbon dioxide and water. 



A. Capable of utilizing ammonium salts as a sole source of nitrogen (Hoyer's 



solution).* 



1. Acetobacter aceti. 



B. Do not utilize ammonium salts as a sole source of nitrogen.* 



1. Forms a thick, zoogloeal, cellulose membrane on the surface of liquid 



media. 



2. Acetobacter xylinum. 



2. Do not form a thick, zoogloeal membrane on the surface of liquid 



media. 



3. Acetobacter rancens. 



3a. Acetobacter pasteurianum. 

 3b. Acetobacter kuetzingianum . 

 II. Do not oxidize acetic acid. 



A. Form pigments in glucose media. 



1. Dark brown to blackish pigment. 



4. Acetobacter melanogenum. 



2. Pink to rose pigment. 



5. Acetobacter roseinn. 



B. Do not form pigments. 



1. Optimum temperature 30° to 35°C. 



6. Acetobacter suboxydans. 



2. Optimum temperature 20° to 25°C. 



7. Acetobacter oxydans. 



* It is not known with certainty whether Acetobacter pasteurianum and Acetobacter 

 kuetzingianum are capable of using inorganic nitrogen as a sole source of nitrogen 

 for growth. However, since these two species are among those first described it is 

 advisable to retain them for the present. See Acetobacter rancens Beijerinck. 



