78 ACTINOMYCETES 



Nitrate: Reduction to nitrite. 



Temperature: Optimum 37°C. 



Antagonistic properties: Strongly effective upon various bacteria. 



Remarks: Soluble brown pigment formed. 



68. Streptomyces niger (Rossi Doria emend. Krassilnikov) comb. nov. 

 (Krassilnikov, N. A., Actinomycetales, Akad. Nauk. USSR, Moskau, 1941, 

 53.) 



Vegetative growth^ Not compact, of soft consistency, lumpy, dark- 

 colored. In old cultures, the mycelium is readily disintegrated into fine 

 particles that can serve for reproduction. 



Aerial mycelium: Produced only on potato and synthetic agar. Sporo- 

 phores produced only seldom; form open spiral, with 3-5 turns. Spores oval. 



Synthetic agar: Growth black; aerial mycelium dark gray. No soluble 

 pigment. 



Nutrient agar: Growth black. Soluble pigment brown. 



Gelatin: Not liquefied in 30 days. 



Milk: No change. 



Starch: No growth. 



Cellulose: No growth. 



Nitrate: No reduction. 



Sucrose: No inversion. 



Temperature: Optimum 25°-30°C. 



Antagonistic properties: Negative. 



Remarks: This is a very unstable species and rapidly dies out. It easily 

 mutates, giving rise to colorless cultures, producing no aerial mycelium. 



69. Streptomyces alboniger Hesseltine et al. (Hesseltine, C. W., Porter, 

 J. N., Deduck, N., Hauk, M., Bohonos, N., and Williams, J. H., Mycologia, 

 1953.) 



Vegetative growth: Growth moist, colorless to yellowish, to dark-brown 

 or black. 



Aerial mycelium: White to pale olive-buff. Irregularly branched sporo- 

 phores, erect to flexuous. Spores catenulate, oval, 0.8 by 1.25 /*. 



Synthetic agar: Growth poor, white; aerial mycelium white. No soluble 

 pigment. 



Nutrient agar: Growth poor, moist, smooth, colorless. No aerial myce- 

 lium. 



Glucose agar: Growth blackish gray; aerial mycelium white. Blackish 

 gray soluble pigment. 



Potato: Growth moist, yellow. White aerial mycelium. Dark, greenish 

 black soluble pigment. 



