SPECIES OF STREPTOMYCES 125 



Aerial mycelium: Profuse in most media, with a marked tendency to 

 produce loose spirals with chains of ellipsoidal conidia. Thick aerial clusters 

 may also be formed. 



Nutrient agar: Growth heavy, colorless, lichnoid, rounded elevations 

 covered with white aerial mycelium; later, submerged margin, round con- 

 fluent growth, aerial mycelium marked in concentric zones. 



Glucose agar: Growth colorless, wrinkled, confluent, with smooth entire 

 margin ; large discrete colonies like flat rosettes ; after 4 months, aerial myce- 

 lium scant, white. 



Gelatin: Colonies minute, colorless; liquefaction. 



Milk: Coagulation; one-third peptonized. 



Nutrient broth: Large, fluffy, white hemispherical colonies, loosely co- 

 herent. 



Glycerol agar: Round, smooth, cream-colored colonies, heavy texture, 

 margin submerged; stiff sparse aerial spikes; after 3 weeks, colonies large 

 (up to 10 mm in diameter) . 



Calcium agar: Spreading colorless growth, pitting medium, submerged 

 undulating margin; aerial mycelium very scant, white. 



Potato agar: Fair growth, partly submerged, covered with grayish white 

 aerial mycelium; medium becomes discolored. 



Dorset's egg medium: Large, round, colorless, scale-like colonies, radially 

 wrinkled; growth brownish, medium discolored in 2 weeks. 



Serum agar: Smooth colorless discoid colonies; marked umbilication after 

 2 weeks. 



Carrot plug: Colorless raised colonies with powdery white aerial myce- 

 lium; after 1 month, very much piled up, aerial mycelium gray; after 2 

 months, superabundant growth around back of plug, confluent, greatly 

 buckled, all-over gray aerial mycelium. 



Antagonistic properties: Positive. 



Source: Streptothricosis of liver. 



147. Streptomyces sterilis (Krassilnikov) comb. nov. (Krassilnikov, N. 

 A., Actinomycetales, Akad. Nauk. USSR, Moskau, 1941, 24, 35, 52). 



In view of the fact that various species of Streptomyces are able to lose 

 the capacity to produce aerial mycelium, either on continued cultivation 

 or by a sort of mutation, cultures are obtained which may be mistaken for 

 nocardias. They can be recognized, however, by the structure of their 

 vegetative mycelium and by their cultural and physiological properties, 

 such as formation of soluble pigments, liquefaction of gelatin, hydrolysis 

 of starch, inversion of sucrose, coagulation and peptonization of milk. 

 Occasionally some are able to revert to the typical streptomycetes or re- 

 gain the capacity to produce aerial mycelium. 



