192 



AGRICULTURAL BACTERIOLOGY 



fermentation may be mistaken for one due to the colon 

 group of bacteria. 



Slimy fermentations. In sugar solutions fermentations 

 are often noted that change the solution into a slimy or 

 ropy liquid. In the manufacture of 

 sugar the syrup may be changed into 

 a mass almost jellylike in consistency, 

 due to the growth of bacteria that 

 possess a gelatinous capsule around 

 the cell. In maple sap a ropy change 

 is often noted, and the same is true of 

 milk. 



This abnormal change seems to be 

 produced most frequently at low tem- 

 peratures. In milk two types of or- 

 ganisms may be concerned. The 

 Norwegians have long used a fer- 

 mented milk of this type as a drink. 

 This prepared milk, known as taetem- 

 jolk, has the taste of ordinary sour 

 milk, but the texture is more or less 

 slimy, depending on how long the 

 fermentation has been allowed to pro- 

 ceed. The organism Bact. lactis 

 longi, used in its preparation, is a 

 member of the Bact. lactis acidi 

 'group, all of which form a slight ropi- 

 ness in milk. The slight increase in 

 viscosity caused thereby is desirable 

 in any fermented milk that is to be 

 used as food, since such change pre- 

 vents the settling of the curd and the appearance of the free 

 whey, which imparts to the milk an unappetizing appear- 

 ance. 



Fig. 40. Ropy Milk 

 It may be drawn out into 

 long threads and does not 

 mix with water when 

 poured into it as does 

 milk that has undergone 

 a more normal type of 

 decomposition 



