100 Microbes and You 



ployed by milk-processing plants makes them difficult to eliminate, 

 and by the time the situation has been cleared up, many customers 

 have found new sources of supply for their milk. 



Ropy bread will result when the flour from which it is made 

 becomes contaminated with encapsulated organisms. Ropiness is 

 due to a breakdown of starch by the organisms and the synthesis 

 of gums from the resulting carbohydrates. Should these forms of 

 bacteria become established in a sugar-refining plant, they are 

 capable of interfering with normal crystallization of the sugar, a 

 costly affair for a large plant. Constant vigilance and strict sani- 

 tary measures must be the watch-word in food-processing plants. 



Many pathogenic bacteria lose their virulence when they are 

 stripped of their slime layer, but Bacillus anthracis, the etiological 

 agent in anthrax, becomes encapsulated after it gets into a 

 susceptible animal, and it may eventuallv destrov the host. It is 

 also possible for sheep to ingest spores of the anthrax bacilli, and 

 these spores can germinate and become encapsulated in vivo with 

 similar fatal results for the host. 



Certain bacteria, particularly the iron bacteria, are capable of 

 secreting or excreting a substance called a sheath, which becomes 

 quite firm in contrast to the slimy nature of representative capsules. 

 Iron compounds may be deposited in these sheaths, and when their 

 volume builds up, these bacteria are capable of completelv occlud- 

 ing water pipes. 



The importance of transfusions with whole blood or with blood 

 plasma in saving human life has been amply demonstrated during 

 World War II and in the Korean conflict, as well as in civilian 

 hospitals. With the source of supply of these vital fluids relatively 

 limited, research has been undertaken to provide needed sub- 

 stitutes. A substance called dextran has been found to be such a 

 possibility. While dextran cannot be considered to be a complete 

 substitute for either whole blood or plasma, its use as a so-called 

 "extender" is proving valuable in restoring the balance so essential 

 in the blood stream in cases of shock. 



Dextran is produced by the action of certain species of the 

 bacterial genus Leuconostoc. These organisms are gram positive 



