SPECIES OF STREPTOMYCES 107 



Habitat: Potato scab. 



Remarks: According to Krassilnikov, Streptomyces poolensis and Strep- 

 tomyces tumuli belong to this group. 



120. Streptomyces praecox (Millard and Burr) comb. nov. (Millard, 

 W. A., and Burr, S., Ann. Appl. Biol., 13, 1926, 580.) 



Vegetative growth: Raised, colorless. 



Aerial mycelium: Well-developed, gray with greenish tinge. Sporophores 

 produce open spirals. Spores spherical or oval, 0.8 /i in diameter. 



Synthetic agar: Growth thin, powdery; aerial mycelium white to olive- 

 buff. 



Synthetic glucose agar: Growth flat with radiating margins; aerial myce- 

 lium white to olive-colored. On cultivation, aerial mycelium is only white. 



Nutrient agar: Growth thin, colorless. Aerial mycelium thin, white. 



Potato: Growth good, cream-colored to light brown; aerial mycelium 

 white to olive-buff. Plug olive-buff to drab; on cultivation, no soluble pig- 

 ment produced. 



Gelatin: Growth good; aerial mycelium abundant, white. Liquefaction 

 medium. 



Milk: Surface growth cream-colored, in form of ring. Aerial mycelium 

 white. Coagulation marked; peptonization rapid. 



Starch: Growth thin, cream-colored, aerial mycelium abundant, white, 

 with greenish tinge. Hydrolysis. 



Nutrient broth: Surface pellicle cream-colored. Aerial mycelium thin, 

 white. No soluble pigment. 



Glucose broth : Flocculated growth at bottom and heavy wrinkled growth 

 at surface; aerial mycelium abundant, white. 



Nitrate: Reduction variable. 



Glycerol synthetic solution : Surf ace growth heavy; aerial mycelium abun- 

 dant, powdery, white. Soluble pigment pale yellow. 



Tyrosinase reaction: Negative. 



Temperature: Grows well at 37.5°C. 



Odor: Very strong. 



Antagonistic properties: Represses growth of Streptomyces scabies. 



Habitat: Knob-like scab of potatoes. 



Remarks: Krassilnikov considers this species related to Streptomyces 

 griseus of Krainsky. 



121. Streptomyces setonii (Millard and Burr) comb. nov. (Millar, W. 

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



Vegetative growth: On synthetic media golden yellow. 



