FAMILY II. ACTINOMYCETACEAE 



735 



fla.ves'cens. L. part. adj. flavescens be- 

 coming gold-colored. 



On media where a firm growth is produced, 

 the vegetative mycelium appears as long, 

 branched, non-septate hyphae, 0.4 to 0.6 

 micron in diameter. In other media, as on 

 nutrient agar and potato, septa are formed, 

 and the mycelium appears in preparations 

 as fragments of very variable size, partly 

 resembling highly branched mycobacteria. 

 In several cases — for instance on nutrient 

 agar at 28° to 30° C, in 5 to 6 weeks-old 

 cultures in glucose broth and in glucose 

 NH4CI solution — short elements assume 

 swollen, fusiform to lemon -shaped forms. 

 The aerial mycelium consists of fairly long 

 hyphae of the same diameter as the vegeta- 

 tive hyphae, not very much branched, 

 without spirals, often clinging together in 

 wisps. A differentiation into spores is never 

 visible b.y direct microscopic e.xamination. 

 Neither is this the case in stained prepara- 

 tions: here the aerial hyphae break up into 

 fragments of quite variable length, from 

 1.2 to 1.5 up to 10 to 12 microns, showing 

 an irregular, granulated staining. 



Gelatin: Slow liquefaction. 



Sucrose agar: Good growth. Vegetative 

 mycelium superficially spreading, much 

 raised and wrinkled, cracking, white to 

 cream-colored, of a dry, but loose and 

 crumbly, consistency. Aerial mycelium 

 scant, thin, white. Faint yellow, soluble 

 pigment after 2 to 3 weeks. 



Glucose agar: Good growth. Vegetative 

 mycelium superficial, wrinkled, honey-yel- 

 low, of a hard and cartilaginous consistency. 

 Aerial mycelium thin, smooth, white. Yel- 

 low, soluble pigment. 



Nutrient agar: Good growth. Vegetative 

 mycelium raised and much wrinkled, first 

 dirty cream-colored, later dark yellowish 

 gray, of a soft, moist, curd-like consistency. 

 No aerial mycelium. No pigment. 



Glucose broth: Rather scant growth. 

 Granulated, yellowish sediment; no sur- 

 face growth. Broth clear. No pigment. No 

 acidity. 



Milk: Coagulated and slowly redissolved 

 with acid reaction. 



Potato: Good to excellent growth. Vege- 

 tative mycelium much raised and wrinkled, 

 first cream-colored, later yellowish brown, 



soft and smeary. No aerial mycelium; no 

 pigment. 



Sucrose is inverted. 



Starch is hydrolyzed. 



Cellulose not decomposed. 



Nitrates are reduced slightly or not at 

 all with various sources of energy. 



Final reaction in glucose-NH4Cl solution, 

 pH 3.9 to 3.6. 



No growth under anaerobic conditions. 



Source: Isolated from soil. 



Habitat: Soil. 



35. Nocardia gibsonii (Erikson, 1935) 

 Waksman, 1953. {Ac.tinornijces gibsonii Erik- 

 son, Med. Res. Council Spec. Rept. Ser. 203, 

 1935, 36; Streptomijces gibsonii Waksman 

 and Henrici, in Manual, 6th ed., 1948, 963; 

 Waksman, in Waksman and Lechevalier, 

 Actinomycetes and Their Antibiotics, Balti- 

 more, 1953, 155.) 



gib.so'ni.i. M.L. gen. noun gibsonii of 

 Gibson; named for Prof. Gibson of Oxford. 



Young, growing mycelium branches pro- 

 fusely at short intervals; later grows out 

 into long, frequently wavy filaments; 

 twisted hyphae also seen on water agar. 

 Power of producing aerial mycelium ap- 

 parently lost. 



Gelatin: Dull white flakes sinking as the 

 medium liquefies; liquefaction complete in 

 12 days. 



Agar: Small, cream-colored, depressed, 

 partly confluent colonies, becoming an ex- 

 tensive, wrinkled, cream-colored skin. 



Glucose agar: Cream-colored, wrinkled, 

 membranous growth. 



Potato agar: Wrinkled, glistening, mem- 

 branous growth. 



Serum agar: Small, moist, cream-colored 

 colonies growing into medium. 



Dorset's egg medium: Small, round, 

 smooth, colorless colonies with conically 

 elevated centers. 



Inspissated serum: Innumerable color- 

 less, pinpoint colonies with scant white 

 aerial mycelium at top; after 8 days, a 

 coherent wrinkled skin with brownish red 

 discoloration at reverse, medium becoming 

 transparent; completely liquefied, pig- 

 mented brown in 15 days. 



Blood agar: Yellowish, confluent bands. 



