Pfizer Handbook of Microbial Metabolites 4 



tene alcohol with, e.g., a steroid alcohol. Many substances are 

 ambiguous and could have been classified in any of several dif- 

 ferent chapters. A substance which contains a sugar, a benzene 

 ring, a terpenoid fragment and a heterocycle will most likely be 

 found under the appropriate heterocycle classification. Some 

 arbitrary decisions have been necessary, but indexing by name, 

 by empirical formula and by producing microorganism should 

 serve most purposes. Again quite generally, progression is from 

 the simple to the complex; sugarlike compounds being con- 

 sidered simple because they resemble the substrate, glucose. 



In order to make the list more coherent a background has 

 been sketched in, emphasizing occurrence and biosynthetic 

 origin. A considerable literature on the biosynthetic origin of 

 microbial metabolites has accumulated. Familiarity wdth it is 

 valuable in interpreting experimental results in structure deter- 

 minations. Several old structures have been revised in the light 

 of this new knowledge. 



Many of the biosynthetic and other metabolic schemes worked 

 out in microorganisms are quite general in occurrence and have 

 been found to be operative in mammalian metabolism. Be- 

 cause bacteria and fungi grow rapidly and are easy and inexpen- 

 sive to handle, they are among the most useful tools in the ex- 

 ploration of metabolic routes. Many of the chemicals in this 

 list were isolated incident to such studies. 



Some chemicals of metabolic significance and of a suitable 

 degree of complexity can be produced economically in quantity 

 by fermentation methods and have found industrial uses. An 

 example is citric acid, which now finds an annual market of 

 thousands of tons. 



The discovery of the effectiveness of the mold product, peni- 

 cilHn, in treating many bacterial infections in man gave tremen- 

 dous impetus to the isolation and screening of microorganisms 

 and their metabolites for antibiotics. The isolation and study 

 of microbial metabolites, formerly a scholarly pursuit in a few 

 academic laboratories, suddenly was supported by the resources 

 of a great industry. Experience showed that a genus of filamen- 

 tous soil organism, the actinomycete ( streptomycete ) , was a 



