28 ACTINOMYCETES 



A number of strains belonging to this group have been isolated. Some of 

 them produce active antibiotics. Several other species described in the 

 literature appear to be related to this group. Here belong S. roseus, S. 

 roseoflavus, and others. 



Streptomyces albus Group 



This group comprises a large number of organisms, characterized by the 

 production of colorless growth on artificial media; the growth is leathery 

 and compact. White aerial mycelium is formed on most media. The spo- 

 rophores are long and produce spirals; the spores are spherical. The various 

 cultures grow well on complex organic and synthetic media. They are not 

 very strongly proteolytic or diastatic. They do not contain any strongly anti- 

 biotic-producing forms, although the first preparation possessing antibac- 

 terial properties ever recorded for an actinomyces was obtained from a 

 member of this group, as shown by Gratia and Dath in 1925; this prepara- 

 tion, actinomycetin, has never obtained any great importance as an anti- 

 biotic agent. This group is widely distributed in nature, especially in soil 

 and in dust. 



Cultures appear to produce active hydrolytic enzymes. Various systems 

 of classification have been proposed for this group. It is to be remembered 

 that at one time all actinomycetes were classified into two groups, (a) 

 A. albus, comprising those that produce an aerial mycelium, and (b) A. 

 chromogenus, comprising those that form a black pigment on organic media. 

 Duche appeared to follow this system, since he designated his whole mono- 

 graph as A. albus. 



Among the other classifications of this group, the one suggested by 

 Krassilnikov is most logical. The separation of the species is based upon 

 the intensity of pigmentation, growth temperatures, odor production, and 

 certain other properties. A typical system is presented here: 

 A. Aerial mycelium whitish or light gray, but not snow-white. 



I. Aerial mycelium produced uniformly over entire vegetative growth. 



1. Cultures are able to grow in or to withstand high temperatures. 



a. Thermophilic 



Streptomyces thermodiastaticus 



b. Thermotolerant 



Streptomyces casei 



2. Cultures do not withstand high temperatures. 

 a. Strongly proteolytic. 



a 1 . Decompose proteins with the formation of H 2 S and NH 3 



Streptomyces putrificans 

 b 1 . Do not form any bad-smelling products. 



Streptomyces^ gelaticus 



