CLASSIFICATION OF THE ACTINOMYCETES 27 



developed; it is usually produced on synthetic media as a thin, rose-white 

 cover, or it is formed only in isolated sectors or spots. The sporophores are 

 straight or spiral -shaped; the spores are spherical to oval, 0.7-0.8 by 0.8- 

 1.0 /x. 



The cultures are not very strongly proteolytic or diastatic. Sucrose is 

 readily inverted. Some of the species belonging to this group are active 

 antibiotic-producers. 



Although a number of species are listed in the literature, only a few have 

 been carefully described. These can be briefly classified as follows: 



A. Colony red to orange-red to dark red. 



I. Proteolytic activity strong. 



Streptomyces bobiliae 

 II. Proteolytic activity weak. 



1. Vegetative growth bright red to red-orange; aerial mycelium 

 poorly developed. 



a. Cultures lyse readily. 



Streptomyces ruber 



b. Chlamydospores produced abundantly in substrate mycelium. 



Streptomyces aurantiacus 



2. Vegetative growth at first yellowish, then red; aerial mycelium 

 well developed . . Streptomyces erythreus 



B. Colony light red or rose. 



I. Proteolytic activity weak. 



Streptomyces roseus 

 II. Proteolytic activity strong. 



1. Does not hydrolyze starch. 



Streptomyces albosporeus 



2. Hydrolyzes starch readily. 



Streptomyces roseodiastaticus 



Streptomyces fradiae Group 



This group is characterized by a colorless to yellowish to orange-colored 

 growth on various media. A well-developed aerial mycelium is produced; 

 it is colored rose to pink (seashell pink) to light orange. No soluble pigment 

 is produced on synthetic or complex organic media. The cultures do not 

 reduce nitrate. They are strongly antagonistic and strongly proteolytic. 

 Some of the strains do not form any spirals in the aerial mycelium, others do. 



Of the two neomycin-producing cultures, 3535 and 3554, the first does 

 not form any spirals and thus agrees with the original description by Waks- 

 man and Curtis. The second produces some spirals of the closed type. There 

 are also differences in pigmentation of the aerial mycelium on synthetic 

 media. 



