98 Perspecfives in Microbiology 



fungi. Impressive advances in this area of mold metabolism 

 have been made with blocked mutants of Neurospora and 

 certain other fungi. For the most part, the biosynthetic 

 pathways examined have proved to be of generalized bio- 

 logical significance. Remarkable promise still exists, how- 

 ever, in relation to biosynthesis of innumerable unique 

 compounds. Who would deny the probable generalized 

 significance of metabolic steps elucidated from a study of, 

 for example, the extensive list of hitherto unknown mole- 

 cules, including aromatics, isolated in significant yields 

 from fungi by Raistrick and his collaborators (12), or of 

 the rather formidable list of antibiotic compounds syn- 

 thesized by fungi? Or the conversion of ionic halogens to 

 organic halogens, a process shown by Clutterbuck and his 

 collaborators (4) to be virtually universal in the 130-odd 

 fungi tested? These few examples suffice to portray the 

 frontiers of unique biosynthesis presented by the fungi. 



For a moment, I should like to return to a point men- 

 tioned earlier, namely, the one-sided emphasis placed on 

 metabolism of carbohydrates by fungi. From the stand- 

 point of obtaining synthesis of cell material and commer- 

 cial products with greatest dispatch, one can appreciate 

 the special interest in the pathways of carbohydrate me- 

 tabolism. Also directing interest toward carbohydrate 

 metabolism is its manifest significance for animal and hu- 

 man nutrition. As a result of these preoccupations, there is 

 the danger of overlooking the perspective of the mold as 

 a biological entity unto itself, and the manner by which 

 it effects biosynthesis of its protoplasm under the condi- 

 tions of survival in nature. 



The question is: to what extent does carbohydrate me- 

 tabolism furnish the energy and carbon for growth of a 

 fungus in its natural habitat? Certain considerations of 

 microecology suggest that the opportunity to utilize solu- 

 ble carbohydrates in nature is a privilege reserved for a 

 very small minority of the vast spectrum of microbiological 



