ESSENTIAL NONMETALLIC ELEMENTS 89 



while F. eumartii perished within 3 weeks when exposed to the same condi- 

 tions, The mycehum of F. oxysporuni grown under reduced oxygen ten- 

 sion was abnormal in its morphology. For further information on the 

 effect of reduced oxygen tension, see Fellows (1928) and Scheffer and 

 Livingston (1937). 



Enormous amounts of sterile air must be supplied to the 10,000- to 

 15,000-gal. tanks used in the production of penicillin and other antibiotics. 

 In the laboratory, aeration is provided by shaking machines of the rotat- 

 ing or reciprocal type. Aeration under these conditions is more uniform 

 than is possible in stationary cultures, W'here submerged and aerial 

 hyphae obtain different amounts of oxygen. This was sho\Mi by Tamiya 

 (1942) who reported that the enzyme systems of submerged mycelium of 

 Aspergillus oryzae are more easily poisoned by cyanide than are those of 

 aerial mycelium. 



In a broad sense, respiration denotes all the enzymatic processes which 

 occur in cells involving a release of energy. There are two general ways 

 in which energy is released by living cells: (1) Cells obtain energy from 

 chemical reactions in which free oxygen is a reactant. The oxidation of 

 metabolite molecules by this process is generally called respiration, or 

 more specifically aerobic respiration. This process is characterized by the 

 intake of free oxygen and the formation of carbon dioxide. If the com- 

 pound being oxidized is composed of carbon, hydrogen, and oxygen only, 

 the products are carbon dioxide, water, and energJ^ (2) Cells also obtain 

 energy from chemical reactions in which free oxygen is not a reactant. 

 This process is called anaerobic respiration, or fermentation. Metabolic 

 processes of this kind are characterized by the production of carbon 

 dioxide, the incomplete oxidation of substrate molecules, and the release 

 of a small amount of energy. 



The reactions involved in the aerobic respiration of glucose may be 

 summarized in a single equation: 



CsHisOe + 60.-^ 6CO2 + 6H2O + 673,000 cal. 



This equation gives no indication of the intermediate stages in this reac- 

 tion or how the energy is utilized by the organism performing the oxida- 

 tion. The number and variety of intermediate reactions do not affect 

 the total amount of energy released. The reactions involved in the 

 alcoholic fermentation of glucose are summarized in the following equation : 



CeHisOs-* 2CH3CH2OH + 2CO2 + 25,000 cal. 



This equation, like the preceding one, gives no indication of the inter- 

 mediate reactions involved. To obtain the same amount of energy, more 

 of a compound must be fermented than when it is completely oxidized. 

 Not all of the energy released by either of these processes is available to 

 the organism (Chap. 4). 



