384 MILK 



organism, and that cows after wading carry it on their coats to 

 the stable. Even ice may, therefore, be the transmitting agent. 

 B. (lactis) viscosus was the cause of the trouble investigated by 

 the writer, and the strain isolated did not grow at all at 37° C. 

 The sliminess was not evident in the milk when delivered to the 

 consumer, but developed after the milk had been kept in a re- 

 frigerator for a few hours. 



After the organism has been introduced into a dairy it is not 

 an easy matter to exterminate it. Superficial steaming of the 

 utensils and machinery is not sufficient. Steam must be appUed 

 until the metal is thoroughly heated. The utensils or machinery 

 may be filled with milk of lime, and this allowed to remain there 

 for several hours before being washed out. 



Buchanan and Hammer found a new type of sHme-forming 

 bacterium in a tube of litmus milk which had been autoclaved. 

 This bacillus digests the casein and leaves a viscous residue. The 

 discoverers named it Bacterium peptogenes. 



Some strains of Bacillus bulgaricus have a strong tendency to 

 slime formation in milk. The shme is particularly evident in 

 young cultures, but after a few days it usually disappears. No 

 capsules have been demonstrated in cultures of this organism. 

 Other members of the group of lactobacilli occasionally produce a 

 slimy milk, but this faculty is readily lost. 



The bacterial products that cause viscosity in milk may be 

 derived either from the carbohydrate or from the protein. When 

 milk-sugar is the mother substance the viscous material is a gum 

 which hydrolyzes either to dextrose or to galactose. The former 

 is known as dextran, the latter as galactan. Galactan is prob- 

 ably more common in milk than dextran. 



When the proteins are the mother substances a mucin is 

 formed which contains a carbohydrate and a protein radical. 

 When heated with acids the presence of both a carbohydrate and 

 a protein can be demonstrated (Buchanan and Hammer). These 

 mucins may be produced by bacteria of the hay bacillus group, 

 by butyric acid bacteria, staphylococci, and by Bacillus pyo- 

 cyaneus. 



The gums and mucins produced by these bacteria are precipi- 

 table by alcohol, and the precipitate easily redissolves in water. 

 According to Buchanan and Hammer a gum is formed when the 

 cell wall of the bacteria is composed of cellulose, and that a mucin 

 is formed when the cell wall is an ectoplasm. 



Slimy milk may be the result of the formation of long chains 

 or, as Buchanan and Hammer^ assume, of extraordinarily intense 



1 A list of the slime-producing organisms with descriptions and review 

 of the literature can be found in the publication of Buchanan and Hammer. 



