134 



ESSENTIALS OF BACTERIOLOGY 



Motile, all possessing flagella, on gelatin surface, a leaf -shaped, 

 thin colony. They all reduce nitrate to nitrite. Gelatin not 

 liquefied. Ferment sugar broth ; some produce acid in milk, 

 some do not. Some form gas in sugar, some not. 



Bacillus Coli (Escherich). Synonyms. Bacterium coli 

 commune; Colon Bacillus. Found (1886) in human feces, in- 

 testinal canal of most animals, in pus and water. 



Form. Short rods, with very slow movement, often asso- 

 ciated in little masses, resembling the typhoid germ, flagel- 



\jy x>U 



>*;^ 



Fig. 57. Bacillus coli communis, from an agar-agar culture (X 1000) 

 (Itzerott and Niemann). 



lated, not forming spores (Fig. 57). Very short round ends; 

 oval forms are found in animal tissues. 



Properties. Does not liquefy gelatin, causes fermentation 

 in saccharine (dextrose) solutions in the absence of oxygen, 

 forming gas. Two parts hydrogen to i part carbon dioxid. 

 Produces acid fermentation in milk; coagulates; its optimum 

 temperature for growth is 37 C.; causes formation of indol in 

 peptone solutions. In bouillon, forms cloudiness with slimy 

 precipitate. Some cultures non-motile. 



