FAMILY IV. EXTEROBACTERIACEAE 



361 



2. Brilliant orange-red pellicle on plain gelatin. 



2. Serratia indica. 



B. Produce enough H2 with the CO2 from glucose to show gas in fermentation tubes. 



1. Acetylmethjdcarbinol produced. 



3. Serratia plymulhica. 



2. Acetj'lmethylcarbinol not produced. 



4. Serratia kiliensis. 

 II. Pigment soluble in water and in alcohol. 



5. Serratia piscatorum. 



1. Serratia niarcescens Bizio, 1823. 

 (Bizio, Polenta porporina, Biblioteca itali- 

 ana o sia Giornale de lettera, scienze e arti, 

 30, 1823, 288; Zoagalactina imetrofa Sette, 

 Memoria storico-naturale sull'arrossimento 

 straordinario di alcune sostanze alimentose 

 osservato nella provincia di Padova I'anno 

 1819. Venezia, 8°, 1824, 51; Monas prodigiosa 

 Ehrenberg, Bericht ii. d. z. Bekannt-ma- 

 chung geeigneten Verhandlungen d. Kgl. 

 preuss. Acad. d. Wissenschaften, 1849, 354.) 



mar.ces'cens. L. part. adj. marcescens 

 pining away, decaying. 



Description taken largely from Breed and 

 Breed (Jour. Bact., 9, 1924, 545). 



Short rods, sometimes almost spherical, 

 0.5 by 0.5 to 1.0 micron, occurring singly 

 and occasionally in chains of 5 or 6 elements. 

 Motile by means of four peritrichous fla- 

 gella. Eight to ten flagella occur on cells 

 grown at 20° to 25° C. (de Rossi, Rivista 

 d'Igiene, I4, 1903, 000). Gram-negative. 



Gelatin colonies: Thin, slightly granular, 

 gray becoming red, circular, slightly undu- 

 late. Medium liquefied rather quickly. 



Gelatin stab: Infundibuliform liquefac- 

 tion. Sediment in liquefied medium usually 

 red on top, white in the depth. 



Agar colonies: Circular, thin, granular, 

 white becoming red. R and S colonies with 

 mucoid variants (Reed, Jour. Bact., 34, 

 1937, 255). 



Agar slant: White, smooth, moist layer, 

 taking on an orange-red to fuchsin color in 

 three or four days, sometimes with a metal- 

 lic luster. 



Broth: Turbid; may form a red ring at 

 surface or slight pellicle; gray sediment. 



Litmus milk: Acid reaction with soft co- 

 agulum. A red surface growth develops. 

 Little or no digestion takes place. 



Potato : At first a white line appears which 



rapidly turns red. The growth is lu.xuriant 

 and frequently shows a metallic luster. 



Indole not produced. 



Production of hj'drogen sulfide: Produced 

 from cysteine, cystine or organic sulfur com- 

 pounds containing either of these molecules. 

 Produced from sulfur but not from sulfites, 

 sulfates or thiosulfates (Tarr, Biochem. 

 Jour., 27, 1933, 1869; also see ibid., 28, 1934, 

 192). 



Produces acetic, formic, succinic andlevo- 

 lactic acids, ethanol, acetylmethylcarbinol, 

 2,3-butylene glycol, CO2 and a trace of H2 

 from glucose (Pederson and Breed, Jour. 

 Bact., 16, 1928, 183). 



Grows poorly or not at all in distilled 

 water containing urea, potassium chloride 

 and glucose. 



Acetylmethylcarbinol is produced 



(Breed) . 



Nitrites produced from nitrates. 



Pigment soluble in alcohol, ether, chlo- 

 roform, benzol and carbon bisulfide 

 (Schneider, Arb. bakt. Hochsch. Karlsruhe, 

 1, 1894, 210). Pigment may diffuse through 

 the agar, i.e., shows solubility in water 

 where strains are very deeply pigmented 

 (Breed). Pigment not produced at 35° C. 



Sodium formate broth (Stark and Eng- 

 land, Jour. Bact., 29, 1935, 26) : Cultures do 

 not produce visible gas (Breed). 



Odor of trimethylamine is produced. 



Aerobic, facultatively anaerobic. 



Optimum temperature, between 25° and 

 30° C. No growth at 37° C. 



Source: Isolated by Bizio and Sette from 

 growth on corn meal mush (polenta). 



Habitat: Found in water, soil, milk and 

 foods and in silk worms and other insects. 



2. Serratia indica (Eisenberg, 1886) 

 Bergey et al., 1923. (Bacillus indicus Eisen- 

 berg, Bakt. Diag., 1 Aufl., 188Q, 1; Micrococ- 



