134 ACTINOMYCETES 



4. Nocardia opaca (den Dooren de Jong) Waksman and Henrici. (den 

 Dooren de Jong, Centrbl. Bakt. II, 71, 1927, 216.) 



Mycelium: Long, curved, irregular and branching filaments or rods, 

 0.8-1.0 by 2-16 /z, or occasionally longer. Few chains or clumps are formed. 

 In older cultures shorter rods or cocci are generally formed. Readily stained. 

 Not acid-fast. Gram-positive. 



Gelatin: Round, convex, whitish, smooth, shining colonies with edges 

 slightly arborescent. Deep colonies: burrs, with slightly irregular processes. 

 Stab: convex, whitish, smooth, resinous, filiform, erose. 



Milk: Grayish pellicle; slightly alkaline. 



Nutrient broth: Turbid with broken white scum, or clear with granular 

 suspension. 



Nitrate: Reduction to nitrite. 



Dorset's egg medium: Spreading, smooth, moist, salmon-colored growth. 



Loeffler's medium: Scanty growth, smooth, moist, light buff-colored. 



Potato glycerol: Dry, rough, crumpled, pink to buff-colored growth. 



Temperature: Optimum 30°C. 



Source: Soils in Great Britain. 



Remarks : Differs from Nocardia corallina and Nocardia polychromogenes 

 in that the cells are much longer than those of the former and much shorter 

 than those of the latter. Grows in smooth convex surface colonies and 

 burr-like deep colonies. Erikson (J. Gen. Microbiol., 3, 1949, 363) added 

 the following characteristics: Soft cream to pink growth on nutrient agars. 

 On synthetic media, growth colorless and thin, producing an initial my- 

 celium, the hyphae dividing rapidly into short rods; addition of 0.01 % 

 MnS0 4 stimulated production of pale pink pigment. Acid-fast cell ele- 

 ments predominated during periods of maximum growth and free air 

 supply. 



No acid from sucrose, lactose, maltose, or glucose; phenol and naph- 

 thalene are utilized as sources of energy. 



5. Nocardia erythropolis (Gray and Thornton) Waksman and Henrici. 

 (Gray, P., and Thornton, H., Centrbl. Bakt. II, 73, 1928, 87.) 



Mycelium: Long uneven-sided rods and filaments, curved and branch- 

 ing, up to 11 y. long by 0.8 /*. Coccoid forms not formed. Stains readily. 

 Not acid-fast. Gram-positive. 



Nutrient agar: Round colonies, 2-3 mm in diameter, convex, watery 

 white; edge entire; deep colonies lens-shaped. Slant: filiform, flat, watery 

 growth; edge undulate. 



Gelatin: After 12 days, round, flat, white, shining colonies; edge entire. 

 Deep colonies: round, smooth. Stab: after 8 to 14 days, convex, white, 



