BACILLUS CO LI 
389 
B. coli is an iUM-ohic, facultatively anaerobic organism which grows 
best at :]7° (\ (Growth ceases below 8° to 10° C, and above 43° to 45° 
C. An exposure of fifteen minutes at 75° C. kills them. In general 
the colon bacillus is somewhat more resistant to physical and chemical 
agents than the typhoid bacillus. Smith and Bryant^ have shown that 
certain strains of 13. coli obtained from the intestinal tracts of calves 
having a diarrheal disease known as "scours" mutate quite promptly 
upon cultivation, and give rise to two types of colonies; one of these is 
like the ordinary type, with reduced virulence, loss of capsular sub- 
stance, and readily agglutinable. The other is characterized by a 
viscid colony. It is an encapsulated and virulent organism. ^ 
Products of Growth. — (fl) Chemical.— BaciWus coli produces indol 
from tryptophan in sugar-free media, and phenolic bodies'* from 
tyrosin under the same conditions. Hydrogen sulphide and ammonia, 
the latter resulting largely from deamination of proteins and protein 
Fig. 52. — Bacillus coli showing flagella. X 1500. (Kolle and Hetsch.) 
derivatives, are also produced in considerable amounts in media 
containing no utilizable carbohydrates."* Similar products may be 
formed in the intestinal tract under certain conditions. The addition 
of utilizable carbohydrates to protein media changes the character of 
the products of metabolism in a noteworthy manner. Under these 
conditions the protein constituents of the media are practically 
unchanged; the sugars are fermented with the production of carbon 
dioxide and hydrogen,^ lactic acid, and smaller amounts of acetic acid 
and formic acid. Glucose, lactose and mannitol are thus fermented;'"' 
1 Smith and Bryant: Jour. Exp. Med., 1927, 46, 133. 
- See Dorothea .Smith: Ibid., p. 155, for the chemistry of the capsular substance. 
3 Hanke and Koessler: Jour. Biol. Chem., 1924, 59, 855. 
•• Kendall and Bly: Jour. Inf. Dis., 1922, 30, 239. 
6 In the proportion H : CO2 = f. Theobald Smith: The Fermentation Tube. The 
Wilder Quarter Century Book, 1893, p. 202. Very exact determinations of the gaseous 
products of fermentation of B. coli have been made by Harden and Walpole (Proc. Roy. 
Soc, 1906, 77, 77, 399. 
^ For equations, see page 75. Also Grey: Biochem. Jour., 1913, 7, 359; Harden: 
Jour. Hyg., 19;15, 5, 488. 
