48 ACTINOMYCETES 



Gelatin: Aerial mycelium white, no soluble pigment. Liquefaction mod- 

 erate. 



Milk: Thick pellicle, aerial mycelium grayish white; no peptonization, 

 no change in pH. 



Starch: Growth poor, thin; aerial mycelium limited; colonies cinnamon- 

 drab. Hydrolysis slight. 



Cellulose: No decomposition. 



Nitrate: Reduction strong. 



Asparagine agar: Aerial mycelium white to pallid quaker-drab; faint 

 yellow soluble pigment. 



Odor: Earthy. 



Antagonistic properties: Produces oxytetracycline, an amphoteric sub- 

 stance active against various bacteria, rickettsiae, and larger viruses; pro- 

 duces also rimocidin, an antifungal agent. 



Remarks: Culture closely related to Streptomyces griseoflavus. 



20. Streptomyces griseoflavus (Krainsky) Waksman and Henrici. 

 (Krainsky, A., Centrbl. Bakt. II, tf, 1914, 639-688.) 



Vegetative growth: Thin cream-colored, later becoming much-folded or 

 lichnoid. 



Aerial mycelium: Aerial mycelium powdery white, appearing first on 

 drier edges of growth. Sporophores straight, abundantly branched; no 

 curvatures, and no spirals produced. 



Synthetic agar: Growth reddish brown to orange, covered with white 

 aerial mycelium; faint yellowish soluble pigment. 



Nutrient agar: Growth cream-colored, covered with white aerial myce- 

 lium; no soluble pigment. 



Potato: Growth lichnoid, cream-colored to brownish, later becoming 

 reddish brown; aerial mycelium powdery white to gray; no soluble pigment. 



Gelatin: Growth cream-colored to brownish, covered with white aerial 

 mycelium. Liquefaction slow, with faint yellowish coloration of liquefied 

 zone. 



Milk: Growth cream-colored to yellowish; aerial mycelium thin white. 

 Peptonization rapid without previous coagulation. 



Starch: Growth cream-colored with brownish center; no aerial mycelium. 

 Hydrolysis limited. 



Nitrate : Reduction to nitrite. 



Yeast-glucose agar: Growth lichnoid, cream-colored to brownish; aerial 

 mycelium white to grayish; soluble yellowish pigment. 



Antagonistic properties: Strongly antagonistic; produces oxytetracycline 

 and rimocidin. 



