100 ACTINOMYCETES 



107. Streptomyces melanocyclus (Merker) Waksman and Henrici. 



(Merker, Centrbl. Bakt. II, SI, 1911, 589.) 



Vegetative growth : Much-folded. 



Aerial mycelium: Dark brown. Spores spherical, 0.9 \i in diameter. Pro- 

 duces red pigment, as well as soluble brown substance, as a result of which 

 culture and substrate become red-brown to almost black with a shade of red. 



Gelatin: Growth poor. Liquefaction rapid. 



Milk: Coagulation; peptonization rapid. 



Starch: Hydrolysis good. 



Cellulose: Decomposition. 



Nutrient broth: Colonies colorless, spherical. 



Nitrate: Reduction to nitrite. 



Sucrose: Inversion. 



Calcium malate agar: Colonies small, flat, orange-red. Aerial mycelium 

 black, occurring along the edges. 



Antagonistic properties: Strong effect upon various bacteria; some strains 

 show no activity. 



108. Streptomyces acidophilus (Jensen) Waksman and Henrici. (Jen- 

 sen, H. L., Soil Sci., 25, 1928, 226.) 



Vegetative growth: Mycelium profusely branched, hyphae 0.6-0.8 n in 

 diameter with homogeneous protoplasm and no visible septa. 



Aerial mycelium: Hyphae 1.0-1.2 n in diameter, somewhat branched, 

 forming either very few or very numerous sinistrorse spirals. Oval conidia 

 1.0-1.2 by 1.2-1.5 m- 



Nutrient agar: No growth. 



Glucose agar: Growth at 25°C good. Substratum mycelium raised, some- 

 what wrinkled, colorless in young cultures. Aerial mycelium thin, white 

 at first, later gray or yellowish brown. 



Potato: Growth good, raised, folded. No discoloration. 



Gelatin: Growth after 10 days very scant, thin, semitransparent, color- 

 less. Liquefaction slow. 



Milk: No growth. 



Starch: Growth at 25°C good. Substratum mycelium flat, smooth, color- 

 less. Aerial mycelium abundant, smooth, white. Diastatic action. 



Nutrient broth: No growth. 



Nitrate: Reduction only a trace in two strains. 



Sucrose: No inversion. 



Czapek's agar: No growth. 



Antagonistic properties: Strongly positive. 



Remarks: Distinctive character: has the ability to live in acid media 

 only. 



