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MANUAL OF DETERMINATIVE BACTERIOLOGY 



Key to the species of genus Aerobacter. 

 I. Glycerol fermented with acid and gas. 

 A. Gelatin not liquefied (rarely liquefied). 



1. Aerobacter aerogenes. 

 II. Glycerol fermented with no visible gas. 



A. Gelatin liquefied. 



2. Aerobacter cloacae. 



1. Aerobacter aerogenes (Kruse) Bei- 

 jerinck. {Bacterium lactis aerogenes Es- 

 cherich, Fortschr. d. Med., 3, 1885, 515; 

 Bacterium lactis Baginsky, Ztschr. f. 

 phys. Chem., 12, 1888,437; not Bacterium 

 lactis Lister, Quart. Jour. Micro. Sci., 

 13, 1873, 380; Bacterium aceticum Bagin- 

 sky, ibid.; Bacillus lactantium Trevisan, 

 I generi e le specie delle Batteriacee, 

 1889, 15; Bacillus lactis aerogenes Stern- 

 berg, Manual of Bacteriology, 1893, 447; 

 Bacillus aerogenes Kruse, in Fliigge, 

 Die Mikroorganismen, 2, 1896, 340; not 

 Bacillus aerogenes Miller, Deutsche 

 med. Wchnschr., 12, 1886, 119; Bacterium 

 aerogenes Chester, Del. Agr. Exp. Sta., 

 9th Ann. Rept., 1897, 53; not Bacterium 

 aerogenes Miller, loc. cit.; Beijerinck, 

 Arch. n6erl. d. sci. exact, et nat., 4, 1900, 

 1 ; Encapsulatus lactis-aerogenes Castel- 

 lani and Chalmers, Manual of Trop. Med., 

 1919, 934; {Encapsulata) Bacillus aero- 

 genes Perkins, Jour. Inf. Dis., 37, 1925, 

 254; Colobaclrum aerogenes Borman, 

 Stuart and Wheeler, Jour. Bact., 48, 

 1944, 358.) From Latin, gas-producing. 



Rods: 0.5 to 0.8 by 1.0 to 2.0 microns, 

 occurring singly. Frequently capsu- 

 lated. (A variety showing a transverse 

 arrangement of the capsule has been 

 named Aerobacter iranscapsulatus by 

 Thompson, Jour. Bact., 28, 1934, 41.) 

 Usually non-motile. Gram -negative. 



Gelatin colonies: Thick, porcelain- 

 white, opaque, moist, smooth, entire. 



Gelatin stab: Thick, spreading, white, 

 opaque surface growth. No liquefaction. 



Agar colonies: Thick, white, raised, 

 moist, smooth, entire. More convex 

 than colonies of Escherichia coli and often 

 mucoid. 



Agar slant: Abundant, thick, white, 

 moist, glistening, spreading growth. 



Broth : Turbid, with pellicle and abun- 

 dant sediment. 



Litmus milk: Acid with coagulation. 

 No peptonization. 



Potato: Thick, yellowish-white to 

 yellowish-brown, spreading with nodular 

 outgrowths over the surface. 



Indole may or may not be formed 

 (Ford, Studies from the Royal Victoria 

 Hospital, Montreal, 1, 1901-1903, 16; 

 Bardsley, Jour. Hyg. (Eng.), 34, 1934, 

 38; Wilson, Med. Res. Council, London, 

 Spec. Rept. Ser. 206, 1935, 161). 



Nitrites produced from nitrates. 



Methyl red test negative (Clark and 

 Lubs, Jour. Inf. Dis., 17, 1915, 160); 

 Voges-Proskauer test positive (Durham, 

 Jour. Exp. Med., 5, 1901, 373); inverse 

 correlation between methyl red and 

 Voges-Proskauer tests (Levine, Jour. 

 Bact., 1, 1916, 153). 



Citric acid and salts of citric acid 

 utilized as sole source of carbon (Koser, 

 Jour. Bact., 8, 1923, 493). 



Uric acid utilized as sole source of 

 nitrogen (Koser, Jour. Inf. Dis., 23, 

 1918, 377). 



Gas ratio : Two or more volumes of 

 carbon dioxide to one of hydrogen formed 

 from glucose (Harden and Walpole, 

 Proc. Roy. Soc. Series B, 77, 1905, 399; 

 Rogers, Clark and Davis, Jour. Inf. Dis., 

 14, 1914, 411). 



Catalase produced. 



Hydrogen sulfide not produced in pep- 

 tone iron agar (Levine, Epstein and 

 Vaughn, Amer. Jour. Pub. Health, 24, 

 1934, 505; Tittsler and Sandholzer, 

 Amer. Jour. Pub. Health, 27, 1937, 1240). 

 More sensitive indicators give positive 



