130 MICRO-ORGANISMS AND FERMENTATION. 



All three species form butyric acid and butyl alcohol from 

 carbohydrates. 



In the water supply of Paris, Perdrix found an anaerobic 

 bacterium (Bacille amylozyme), which occurs in the form of 

 motile threads, four to six times as long as they are broad. 

 This converts saccharose into acetic and butyric acids, with 

 evolution of hydrogen and carbon dioxide, and it also produces 

 amyl and ethyl alcohols. The optimum for its growth is 

 35 C. On slices of potato it forms whitish round colonies, 

 which gradually liquefy the substratum. This species is very 

 sensitive to acids. The spores can withstand ten minutes' 

 heating to 80 C. 



Bac. orthobutylicus was isolated by Grimbert from seeds 

 of the leguminosse. It was separated by heating for one minute 

 at 100 C. Its spores survive this treatment. The species 

 is anaerobic, and forms motile rods two to four times as long 

 as they are broad, with rounded ends. In these rods two 

 and three spores may occur. Its fermentation products are 

 chiefly butyric acid, butyl alcohol, and acetic acid, together 

 with carbon dioxide and hydrogen. It ferments saccharose, 

 maltose, lactose, and glycerine. It hydrolyses starch, and 

 converts dextrose into maltose. Grimbert proved by detailed 

 experiment that the length of fermentation, the concentration, 

 the reaction of the liquid, and the conditions of growth all 

 influence the amounts of the fermentation products. Thus 

 with an acid reaction the amount of alcohol increased and the 

 formation of acid simultaneously decreased. On the other hand, 

 the quantity of alcohol diminished and that of acid increased 

 when the liquid was neutralised with calcium carbonate. 



Amongst other workers in this field may be mentioned 

 Botkin and Fliigge, who isolated a species from milk by heating 

 for one and a-half hours in boiling water or in a current of 

 steam, the spores surviving this treatment ; v. Klecki, who 

 cultivated Bac. saccharobutyricus from cheese ; v. Hibler, who 

 examined pathogenic varieties, and proved that one and the 

 same species may occur in different shapes not only as indi- 

 viduals, but also in colonies, according to the nature of the 

 substratum. By cultivation in gelatine without sugar the 

 different forms of colonies may be most clearly distinguished. 



