DIVISION II 



NUTRITION AND METABOLISM 



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INTRODUCTION* 



The nutrition and metabolism of microorganisms are based on many 

 of the same principles which regulate animal and plant metabolism; 

 in many ways microorganisms are more closely related to animals than 

 to plants, if viewed from the standpoint of their food, their mode of 

 digestion, and their general physiological nature. Aside from the 

 many specific physiological processes peculiar to microbial life as 

 in the case of life without oxygen (anaerobiosis) and in the ability of some 

 species to use free nitrogen gas, the functioning of microorganisms 

 accords with the cellular metabolism and nutritive principles of 

 the more highly developed organisms. Since it will be desirable 

 frequently to refer to plant and animal nutrition in the course of 

 this discussion, these principles, therefore, are briefly discussed in 

 the following paragraphs. 



Green plants feed only on inorganic substances. They assimilate 

 carbon dioxide (COz) from the air which unites with water, nitrates, 

 potassium, calcium, and other salts of the soil and form the body sub- 

 stances of the plant. The cellulose, starch, sugar, protein and all other 

 compounds constituting the plant cells are produced from these simple 

 inorganic substances. Animals feed upon animals and plants. Unlike 

 plants they utilize the oxygen of the air and give off carbon dioxide 

 (CO 2 ). Out of these materials, together with water, life is sustained. 

 Although in details animals, plants and microorganisms differ quite 

 widely, the general laws of nutrition and metabolism are very similar. 



The methods by which microorganisms secure their food vary. 

 Molds take up their food through the mycelium after it has been pre- 

 pared by the action of digestive agents, enzymes, secreted by the cells. 

 If the food be suitable for the life of the cell without change, of course, 

 these digestive agents are not needed. When properly altered, such 





* Prepared by Otto Rahn. Revised by Editor. 



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