Gelatin stab: Crateriform liquefaction. No pellicle. Agar slant: Gray, smooth, filamentous. Broth: Turbid with delicate pellicle. Litmus milk: Acid; coagulated; pep- tonized. Potato: Brownish yellow to brownish red color. Indole is produced. Hydrogen sulfide is produced. Acid and gas from glucose broth (Leh- mann and Neumann, op. cit., 1896, 238). Aerobic, facultative. Optimum temperature, between 25° and 30° C. Distinctive characters: There does not seem to be any real difference between this organism and Aeromonas liquefaciens Kluy- ver and van Niel. Schaperclaus (Fisch- krankheiten, Braunschweig, 1 Aufi., 1935, 46; Ztschr. f. Fischerei, 37, 1939, 7) recog- nizes definite varieties of this species: some are non-pathogenic, others are patho- genic to carp, and still others are patho- genic to eels. Source: From Chemnitz tap water (Zim- mermann). Commonly found in water of the River Main (Lehmann and Neumann, op. cit., 238; also see op. cit., 7 Aufl., 2, 1927, 47). Habitat: Found in water supplies, es- pecially those in which carp, eels and other fishes occur. Causes an infectious edema in carp (Cyprinus) (Schaperclaus, op. cit., 1930, 289; see Zent. f. Bakt., II Abt., 105, 1942, 49) and other fishes.
3. Aeromonas hydrophila (Chester, 1901) Stanier, 1943. {Bacillus htjdrophilus fuscus Sanarelli, Cent. f. Bakt., 9, 1891, 222; Bacillus hydrophilus Chester, Manual Determ. Bact., 1901, 235; Proteus hydro- philus Bergey et al.. Manual, 1st ed., 1923, 211; Stanier, Jour. Bact., 46, 1943, 213.) hy.dro'phi.la. Gr. noun hydor water; Gr. philus loving; M.L. adj. hydrophilus water- loving. Description taken from Emerson and Norris (Jour. Exp. Med., 7, 1905, 32) and from E. M. Miles and A. A. Miles (Jour. Gen. Microbiol., 5, 1951, 299). Rods, 0.6 by 1.3 microns, occurring singly and in chains. Motile, with a single polar flagellum (Kulp and Borden, Jour, of Bact., U, 1942, 673). Gram-negative. Gelatin colonies: Small, circular, gray, translucent, stippled. Gelatin stab: Napiform liquefaction. Agar colonies: Whitish, raised, moist, stippled. Horse blood agar colonies: 2 to 3 mm in diameter, round, entire, raised, smooth, moist, semi-translucent, grayish white, forming a dirty brown-yellow coloration after 3 to 5 days at room temperature; marked hemolysis. Agar slant : Thin, whitish, glassy, spread- ing, becoming yellowish and opalescent. Broth: Turbid, with heavy pellicle. Loeffler's serum: Growth abundant, but no digestion. Litmus milk: Acid; coagulated; pep- tonized. Potato: Yellowish brown, moist, slightly raised. Indole is produced. Nitrites produced from nitrates. Ammonium sulfate, uric acid and aspara- gine may serve as sources of nitrogen. Catalase produced. Hydrogen sulfide produced. Urea not attacked. Methylene blue reduced. Acid and gas from glucose, galactose, fructose, mannose, maltose, sucrose, man- nitol, glycerol and starch. Acid and gas from salicin at 22° C. but not at 37° C. Acid from glycogen and dextrin. Glucose fer- mented with the production of 2,3-butane- diol. Lactose, arabinose, raffinose, rham- nose, dulcitol, sorbitol and inositol not attacked. In the fermentation of beet molasses, Murphy, Watson, Muirhead and Barnwell (Canad. Jour. Tech., 29, 1951, 375) found this organism to yield up to 96 per cent of theoretical 2,3-butariediol and acetoin. This is a higher yield than the same authors found for Aerobacter aerogenes. Starch hydrolyzed. Gas ratio HjrCOs = 1:4.71. Methyl red negative, acetylmethylcarbinol positive, indole negative, citrate positive (Speck and Stark, Jour. Bact., U, 1942, 697). Aerobic, facultative. Optimum temperature, 37° C.
