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THE ACTINOMYCETES, Vol. II 



Figure 13. N. opaca (V. erythropolis), showing scheme of branching; glycerol nutrient agar, first 

 sketch 10 hours incubation; others at hourly intervals (Reproduced from: McClung, N. M. Lloydia 12: 

 153, 1949). 



Synonyms: Nocardia crystallophaga (Gray 

 and Thornton); N. erythropolis (dray and 

 Thornton); Proactinomyces opacus (Jensen). 



Morphology: Growth lustrous, rose-col- 

 ored to red. Hyphae long, curved, irregular 

 and branching, breaking up into rods and 

 cocci. Not acid-fast. Gram-positive (Fig. 13). 



Potato-glycerol agar: Growth dry, rough, 

 crumpled, pink to buff-colored. 



Gelatin: Colonies round, convex, whitish, 

 smooth, shining, with edges slightly ar- 

 borescent. Stab: convex, whitish, smooth, 

 resinous, filiform, erose. No liquefaction. 



Egg medium: Growth spreading, smooth, 

 moist, salmon-colored. 



Potato: Growth covered with tufts of 

 aerial hyphae. 



Milk: Grayish pellicle. No coagulation, no 

 peptonization. Reaction slightly alkaline. 



Nitrate reduction: Positive. 



Starch: Noi hydrolyzed. 



Sucrose inversion: Negative. 



Carbon sources: Sat mated, long chain 

 aliphatic hydrocarbons are utilized as sources 

 of energy. 



Temperature: Optimum 30°C. 



Source: Seldom found in soils. 



Remarks: Differs from X. corallina and 

 N. polychromogenes in that the cells are 

 much longer than those of the former and 



