Molds as Metabolic Models 95 



Although this instruction has been available in the area 

 of mold metabolism for more than a half-century, it should 

 not be inferred that capitalization to the highest degree 

 possible has already been accomplished with the fungi 

 themselves. Nevertheless, I am confident that the principle 

 of high substrate concentration as practiced with fungi 

 will, when properly manipulated, stand with other ac- 

 cepted means of obtaining vital information relative to 

 the pathways of oxidative breakdown of virtually any 

 soluble compound by microorganisms. 



Two notes of caution seem desirable, to anticipate re- 

 sults inconsistent with this thesis. First, it should be recog- 

 nized that the initial organism tested on the particular 

 substrate may not display a useful performance. Whereas 

 the biochemist might conclude that that finished it, the 

 microbiologist simply moves in with a magical bag of tricks 

 peculiar to his profession — an inexhaustible series of dif- 

 ferent strains and species of microorganisms. The second 

 note relates to satisfying the oxygen demand of organisms 

 developing in media of high substrate content. As methods 

 for achieving this are adequately documented in numer- 

 ous literature sources, it is only necessary to comment here 

 that the problem is particularly acute in mold cultures 

 because of the tissue-like nature of the growth. 



Cafabolic Mechanisms of Fungi 



■ Among living things, by and large, the fundamental 

 differences in metabolism appear to be those concerned 

 with the procurement of energy, that is, the catabolic ac- 

 tivities. To put it another way, and excluding autotrophic 

 forms, the oxidative degradation of each of the infinite 

 variety of single organic compounds existing in nature 

 furnishes the energy and building blocks for at least one 

 species of microorganism; otherwise, during the course of 

 geologic time the particular compound would have ac- 



