212 AGEICULTUEAL AND INDUSTRIAL BACTEEIOLOGY 



moist, later dry, and finally wrinkled, while the medium 

 below the surface remains quite clear. The bacteria occur 

 in chains, although greatly elongated filaments may be 

 observed. This organism produces a much larger amount of 

 slime than the Acetobacter aceti, and the slime turns blue 

 when potassium iodide or iodine is added. The involution 

 forms are particularly abundant. Upon beer-wort and 

 beer-wort gelatin the organism grows readily. It has a high 

 power of oxidizing alcohols to corresponding acids, ethyl 

 alcohol being rapidly transformed to acetic acid, propyl 

 alcohol to propionic acid, and dextrose, to gluconic acid 



(CH30H(CH0H),C00H). 



Acetobacter orleanense is regarded as one of the most 

 common causes of acetic fermentation in fruit juices such 

 as the wines and ciders. It differs only in minor morpho- 

 logical and physiological characters from species of the 

 Acetobacter previously described. It can produce acid 

 from many sugars but best where it can oxidize alcohol to 

 acetic acid. It may be noted that this organism, as well as 

 other species of Acetobacter may continue the action beyond 

 the point of complete oxidation to acetic acid, and may also, 

 when the alcohol supply has been exhausted, oxidize the 

 acetic acid to carbon dioxide and water. This makes it 

 necessary to pasteurize or to seal vinegar from the air when 

 it has been prepared, otherwise the same organisms which 

 produced it will destroy it or cause it to "lose its strength." 



The Acetobacter schiltzenbacJiii may be taken as a repre- 

 sentative of the species which have been described in the 

 so-called quick process of vinegar manufacture. While it 

 grows readily upon ordinary culture media, it does not 

 produce a heavy film upon the surface of liquids. It is, 

 therefore, not an organism which would ordinarily bring 

 about the transformation of cider or wine into vinegar by 

 the slow process requiring film formation. The bacterial 



