242 



THE ACTINOMYCETES, Vol. I 



found to exert any antagonistic effects upon 

 other microorganisms. 



Numerous other compounds were isolated 

 from various cultures of actinomycetes. They 

 are described in detail in Chapters 31-40 

 (Volume III). 



The Role of" Antibiotic Biosynthesis in 

 the Metabolism of Actinomycetes 



According to Perlman, the role of antibi- 

 otic biosynthesis in the metabolism of actino- 

 mycetes is of considerable significance. An 

 analysis of the cells of S. griseus suggests that 

 the amino acids do not differ in nature 

 from those in other actinomycetes. The fact 

 that a substantial quantity of streptomycin 

 (usually more than half of that produced) 

 occurs bound to the mycelium suggests that 

 the antibiotic may form a part of the cell wall 

 of the organism. This bound streptomycin 

 may be released (Table 67) by treatment of 

 the cells with acid, alkali, or ionizable salts, 

 but not by disintegration of the cells by sonic 

 energy, bacteriophage, or enzymatic treat- 

 ment. Considerable amounts of other anti- 

 biotics, including streptothricin, the neomy- 

 cins, chloramphenicol, and chlortetracycline, 

 have been found to occur bound to the my- 

 celium of the respective actinomycetes and 

 may be released by treatment with acid, 

 alkali, or ionizable salts. This binding does 

 not appear to be a simple ion-exchange phe- 



nomenon, since addition of streptomycin to 

 the mycelium of the organism does not re- 

 sult in its absorption, and the "binding" 

 power of the mycelium is apparently not a 

 function of its weight (Perlman and Lan- 

 glykke). 



Chemical Structure and Antimicrobial 

 Activities of Actinomycete Antibi- 

 otics 



The effect of chemical structure upon the 

 biological activities of antibiotics in general 

 and of actinomycete antibiotics in particular 

 is discussed in detail in Chapter 31 (Volume 

 III). It is sufficient to say here that any 

 slight modification of the molecule may cause 

 a profound change in the activities of the 

 antibiotic. 



As a rule, the chemical or enzymatic deg- 

 radation of an antibiotic results in its loss of 

 activity. This is not always the case, how- 

 ever, as shown for neamine, a degradation 

 product of the neomycins ; it retains its anti- 

 biotic properties, although the spectrum is 

 changed. Xakamura has shown that an anti- 

 biotic of the luteomycin type (C26H33NO12) 

 gave, on acid hydrolysis, a greenish black 

 substance, designated teomycic acid (C17- 

 H23XO11), which retained its antibiotic prop- 

 erties. However, actinomycin treated with 

 an enzyme preparation completely loses its 

 activity, as shown preA'iously. 



