238 



THE ACTINOMYCETES, Vol. I 



2 4 6 8 10 



UNITS OF GRISEIN /ml 



Figure 90. Effect of antibiotic concentration 

 on development of resistance by E. coli in agar 

 media: O, Gri.sein alone; A, Grisein + strepto- 

 mycin 1 Mg/ml; n Grisein + streptomycin 2/xg/ml. 

 (Reprodnced from: Reynolds, D. M. and Waks- 

 man. S. A. J. Bacteriol. 55: 750, 1948). 



The Macrolides 



The first of these antibiotics (erythromy- 

 cin) was isolated l)y JVIcCkiire et al. (1952) 

 from a culture of »S'. enjthreus. It is a basic 

 compound, soluble in water, alcohol, and 

 other organic s()lv(Mits. It has significant ac- 

 tivity against gram-positive organisms and 

 some of the more important gram-negati\'e 

 bacteria, such as the Neisseria, Ilemophibis, 

 and Brucella groups; it is also active upon 

 rickettsiae, the larger viruses, and some pro- 

 tozoa. 



A number of other ervthromvciu-like com- 



pounds ha^•e been isolated and descril)ed un- 

 der a variety of names, such as picromycin, 

 magnam,ycin (carbomycin), oleandomycin, 

 methymycin, and spiromycin. 



Novobiocin 



This antibiotic is produced by S. niveus 

 and by S. spheroides. It has been isolated 

 simultaneously in different laboratories and 

 described under different names (strepto- 

 nivicin, cathomycin, cardelmycin, vulcano- 

 mycin, etc.). It is highly active against Staph, 

 aureus, as well as against a variety of other 

 gram-positive and some gram-negative bac- 

 teria, but it causes allergic dermatitis. 



Streptovariciii 



This orange-red group of antibiotics, 

 which contains at least five closely related 

 components, was isolated from the culture of 

 an organism described as S. spectabilis. It is 

 active against various gram-positive, gram- 

 negative, and especially acid-fast bacteria. 



The Polyenes 



Most of the previously listed antibiotics 

 are active primarily on bacteria and have 

 only a limited activity on true fungi. There 

 are, however, a number of antibiotics pro- 

 duced by actinomycetes that have a highly 

 selective activity upon fungi. As pointed out 

 previously, the first survey of the distribu- 

 tion of antifungal properties among actino- 

 mycetes was made by Alexopoulos. A large 

 nimiber of compounds ha^'e now been 

 isolated and described under the names of 

 actidione, fradicin, thiolutin, nystatin, candi- 

 cidin, ascosin, candidin, trichomycin, anti- 

 mycoin, filipin, amphotericin, and others. 

 Most of them belong to the polyenes. Only 

 a few of them, notably nystatin and tricho- 

 mycin, have found practical application. 



Recently, Ball et al. mad(^ a comprehensive 

 study of the production of polyene antibiot- 

 ics l)y species of Streptomijees. These polyenes 

 w(M-e grouped together on the basis of cer- 



