Starch agar: Cream-colored growth with brownish center; no aerial mycelium. Glucose agar: White aerial mycelium is slowly formed. Yeast-glucose agar: Lichenoid, cream- colored to brownish growth; white to gray- ish aerial mycelium; soluble yellowish pig- ment. Glucose broth: Flaky growth. Milk: Cream-colored to yellowish growth; aerial mycelium thin, white. Rapidly pep- tonized without previous coagulation. Potato: Lichenoid, cream-colored to brownish growth, later becoming reddish brown; aerial mycelium powdery white to gray; no soluble pigment. Starch is weakly hydrolyzed. Esculin is attacked. Good growth on cellulose. Nitrites produced from nitrates. Aerobic. Optimum temperature, 35° C. Antagonistic properties: Strongly antag- onistic. Source: Isolated from soil. Habitat: Soil. 21. Streptomyces aureofaciens Duggar, 1948. (Ann. N. Y. Acad. Sci., 51, 1948, 177; U. S. Patent 2,482,055, Sept. 13, 1949.) au.re.o.fa'ci.ens. L. neut.n. aurum gold; L. part. adj. faciens producing; M.L. part, adj. aureofaciens golden-making. Vegetative growth: Mycelium hyaline, becoming yellow in 2 to 3 days, later golden tan to tawny. Aerial mycelium: White, becoming brown- ish gray to dark, drab-gray in 5 to 10 days. Sporophores straight, flexuous; no spirals. Spores spherical to ellipsoidal, longest di- ameter 1.5 microns. Gelatin: No liquefaction. Agar: Good, light brownish growth. No aerial mycelium. No soluble pigment. Asparagine-meat extract glucose agar: Hyaline growth changing to orange-yellow. Aerial mycelium abundant, white, changing to deep gray or dark gray with tawny re- verse. Faint yellowish soluble pigment. Milk: Limited, yellow-brown growth. No coagulation or peptonization. Potato: Wrinkled, orange-yellow growth. Color of plug unchanged. Antagonistic properties: Produces chlor- tetracycline, an amphoteric compound containing both nitrogen and non-ionic chlorine, active against various bacteria, rickettsiae and the larger viruses. Comments: The numerous natural and induced variants of S. aureofaciens display wide variations in color of vegetative growth ranging from pale yellow to reddish brown and even occasionally greenish depending upon the composition of the nutrient sub- strates and environmental conditions. The color of aerial mycelia is influenced by sporulation. Yellowish, soluble pigment often not discernible. Loose spirals are in- frequently encountered. Source: Isolated from soil. Habitat: Presumably soil. 22. Streptomyces albidoflavus (Rossi- Doria, 1891) Waksman and Henrici, 1948. {Streptotrix (sic) albido-flava Rossi-Doria, Ann. d. 1st. d'Ig. sper. d. Univ. di Roma, 1, 1891, 407; Waksman and Henrici, in Manual, 6th ed., 1948, 949.) al.bi.do.fla'vus. L. adj. albidus white; L. adj. flavus yellow; M.L. adj. albidoflavus whitish yellow. Description taken from Duche (Encyclo- pMie Mycologique, Paris, 6, 1934, 294). Gelatin: Punctiform colonies with white aerial mycelium on surface of liquid; no soluble pigment; rapid liquefaction. Agar: Cream-colored growth covered with fine white aerial mycelium; yellow soluble pigment. Synthetic asparagine agar: Growth be- comes rapidly covered with white aerial mycelium, later becoming whitish yellow; brown on reverse side; yellowish soluble pig- ment. Tyrosine agar: Fine growth with orange- yellow on reverse side; medium becomes colored yellowish to yellowish rose. Synthetic asparagine solution: Long branching filaments, 0.6 micron in diame- ter. Thicker aerial mycelium producing irregular spores; flaky growth dropping to bottom of tube. Surface growth becomes covered with yellowish white aerial myce- lium; brownish on reverse side; soluble pig- ment yellowish. Peptone solution: Rapid, much folded
