106 ACTINOMYCETES 



Gelatin: Surface growth wrinkled; aerial mycelium white. Liquefaction 

 rapid. No soluble pigment. 



Milk: Surface growth cream-colored. No coagulation; peptonization 

 rapid. 



Starch: Growth spreading, thin, colorless; no aerial mycelium. Hydrol- 

 ysis. 



Glucose broth: Growth limited; aerial mycelium white to gray. 



Tyrosinase reaction : Negative. 



Nitrate: Reduction. 



Glycerol synthetic solution: Good growth on surface of medium; num- 

 erous star-like colonies throughout medium; aerial mycelium scant, white 

 to mouse-gray. 



Temperature: Only slight growth at 37.5°C. 



Habitat: Raised, smooth scab. 



119. Streptomyces gracilis (Millard and Burr) comb. nov. (Millard, 

 W. A., and Burr, S., Ann. Appl. Biol., 18, 1926, 580.) 



Vegetative growth: On synthetic media, dark brown, producing a soluble 

 brown substance. 



Aerial mycelium: Dark olive. Spiral-forming sporophores; spores oval 

 or spherical, 0.8-0.9 by 0.8 p. 



Synthetic sucrose agar: Growth fern-like, pale gray, covered with scant 

 gray to buff aerial mycelium. Soluble pigment cream-colored. 



Synthetic glucose agar: Growth smooth, pale olive-gray. Aerial mycelium 

 abundant, white, smooth. Soluble pigment cream-colored. 



Nutrient potato agar: Growth vinaceous buff to dark brown or almost 

 black. Aerial mycelium gray. Soluble pigment light golden brown. 



Potato: Growth good, echinate, covered with abundant olive-gray to 

 buff aerial mycelium. Plug light brown. 



Gelatin: Growth gray, covered with white aerial mycelium. Liquefaction 

 rapid. Soluble pigment pink to dark golden brown. 



Milk: Surface growth good; aerial mycelium white in the form of a ring 

 and specks on surface. Coagulation slow, followed by rapid peptonization. 



Starch: Hydrolysis. 



Glucose broth: Growth good both on surface and on bottom. Aerial 

 mycelium abundant, olive-buff. Soluble pigment light golden brown. 



Nitrate: Reduction. 



Glycerol synthetic solution: Growth good on surface and throughout 

 medium. Aerial mycelium abundant, white to olive-buff. 



Tyrosinase reaction: Negative. 



Temperature: Grows well at 37.5°C. 



