948 



MANUAL OF DETERMINATIVE BACTERIOLOGY 



black. Odor fairly strong. Microscopi- 

 cally two types of mycelium are found : 

 the thin, branching filaments of the sub- 

 stratum, and the thick filaments of the 

 aerial mycelium. The aerial mycelium 

 fragments not very rapidly, producing a 

 few conidia, spherical and oval, 1.2 to 

 1.5 by 1.2 to 2.3 microns. These often 

 occur in chains. 



Czapek's solution: Colonies large, 2 to 

 3 mm in diameter, appearing at the bot- 

 tom and surface of the solution, but none 

 throughout the medium. Colonies blu- 

 ish in color, with a regular margin. Me- 

 dium not colored. 



Potato plug : Growth at first very slight, 

 but after 48 hours develops into a yellow- 

 ish-gray continuous thick smear which 

 later turns brown, with a white aerial 

 mycelium covering the growth. Medium 

 not colored. 



Source : Isolated once from the upland 

 California soil. 



Habitat: Soil. 



34. Streptomyces griseus (Krainsky) 

 comb. nov. {Actinomyces griseus Krain- 

 sky, Cent. f. Bakt., II Abt., 41, 1914, 

 662. ) From M. L. griseus, gray. 



Branching filaments ; a few spirals have 

 been observed. Conidia rod-shaped to 

 short cylindrical, O.S bj' 0.8 to 1 .7 microns . 

 Aerial mycelium greenish-gray. 



Gelatin stab : Greenish-yellow or cream- 

 colored surface growth with brownish 

 tinge. Rapid liquefaction. 



Synthetic agar : Thin, colorless, spread- 

 ing growth, becoming olive buff. Aerial 

 mycelium thick, powdery, water-green. 



Starch agar: Thin, spreading, trans- 

 parent growth. 



Glucose agar: Growth elevated in cen- 

 ter, radiate, cream-colored to orange, 

 arose margin. 



Plain agar: Abundant, cream-colored, 

 almost transparent growth. 



Glucose broth : Abundant, yellowish 

 pellicle with greenish tinge, much folded. 



Litmus milk: Cream-colored ring; co- 



agulated with rapid peptonization, be- 

 coming alkaline. 



Potato: Yellowish, wrinkled growth. 



Nitrites produced from nitrates. 



The pigment formed is not soluble. 



Starch is hydrolyzed. 



Aerobic. 



Optimum temperature 37°C. 



Different strains of this organism pro- 

 duce different antibiotics. One of these, 

 streptomycin, was isolated in crystalline 

 form. It is active against a large num- 

 ber of bacteria and actinomycetes, but 

 not against fungi and viruses. It is not 

 very to.\ic to animals, and has found 

 extensive application in the treatment of 

 various diseases, mostly caused by 

 Gram-negative bacteria and certain 

 forms of tuberculosis. 



Source: Garden soil. ' 



Habitat: Soil. 



35. Streptomyces griseofiavus (Krain- 

 sky) comb. nov. {Actinomijces griseo- 

 fiavus Krainsky, Cent. f. Bakt., II Abt., 

 41, 1914, 662.) From M. L. griseus, gray 

 and haiin flavus , yellow. 



Conidia oval, 1.2 microns. 



Gelatin colonies : Yellowish. Concentric 

 rings. 



Gelatin stab : Rapidly liquefied. 



Plain agar: Colonies yellowish, with 

 white aerial mycelium. 



Ca-malate agar : Large colonies covered 

 with yellow to greenish-gray aerial my- 

 celium. 



Glucose agar : White aerial mycelium is 

 slowly formed. 



Starch agar : White aerial mycelium. 



Glucose broth : Flaky growth. 



Litmus milk: Peptonized. 



Potato: Yellowish growth, aerial my- 

 celium gray. 



Nitrites produced from nitrates. 



Weakly diastatic. Acts on esculin. 



Grows well on cellulose. 



Aerobic. 



Optimum temperature 35°C. 



Habitat: Soil. 



