METABOLISM OF MICROORGANISMS 



36; 



tion of their elementary composition. Some of these antibiotics are well- 

 characterized structurally, but most of them are poorly defined chemical 

 compounds. One reason why so little is known regarding the chemical 

 nature of many antibiotics is the fact that they are too toxic for clinical 

 use. Toxicity removes one of the strong incentives for determining 

 their structure. This is unfortunate, because a knowledge of the struc- 

 ture of a toxic substance is perhaps as important as an understanding 

 of the make-up of the less toxic substance. There is a fine opportunity 

 for qualified chemists in this field. 



The best known antibiotic in actual use is of course penicillin, but 

 since it is a mold product it will be discussed in the section on molds. 

 The other antibiotics are produced either by bacteria or streptomycetes. 

 The latter are classified as bacteria, although they have mold-like char- 

 acteristics, for example, growth in long thread-like filaments. Each of 

 these antibiotics will be discussed separately. 



Streptomycin. This antibiotic was discovered by Waksman and asso- 



H NH 



I II 

 N— C— NH2 



HO I 



I /C-H/H 



H. 







C— H 



H2N— C— N— C>^ ^C— H 

 II ^ C \ 



Streptidine moiety 

 (gives basic property) 



O 



H— C 



I 

 0=C— C— OH 



H C-H 



O- 



C— H 



CH3 



Streptose moiety 

 (reducing property) 



CH3-N— C-H 



H^ I 

 O H— C-OH 



I 

 HO— C— H 



I 



C-H 



I 

 CHoOH 



N-Methyl-L-glucosamine 



' — Streptobiosamine ■ 

 moiety 



Streptomycin 

 (free base) 



ciates in 1944 and is produced by the microorganism Streptoinyces griseus. 

 Like most microorganisms, S. griseus produces several other antibiotics, 

 namely, mannosidostreptomycin, a combination of mannose and strepto- 

 mycin; actidione, an antifungal compound (C15H23NO4) ; and grisein 

 (C40H61N10O00SFC) . By selection, strains of S. griseus have been obtained 



