Aerial mycelium: Well developed, white. Sporophores produce spirals; spores spheri- cal to ellipsoidal. Gelatin: Slow liquefaction. Synthetic agar: Colorless growth. Aerial mycelium well developed, white. Milk: Not coagulated; not peptonized. Potato: Brownish growth. Aerial myce- lium light gray. Sucrose is inverted. Starch is actively hydrolyzed. Good growth on cellulose. Nitrites produced from nitrates. Optimum temperature, 65° C. Source: Isolated from the stomach con- tents of a rabbit. Habitat: Unknown. 116. Streptomyces thermofuscus (Waksman et al., 1939) Waksman and Hen- rici, 1948. (Actinomyces thermojxiscus Waks- man, Umbreit and Cordon, Soil Sci., 47, 1939, 49; Waksman and Henrici, in Manual, 6th ed., 1948, 957.) ther.mo.fus'cus. Gr. noun therme heat; L. adj. fuscus dark, dusky; M.L. adj. ther- mofuscus (probably intended to mean) thermophilic and dusky. Aerial mycelium: Hyphae spiral-shaped; conidia produced. Gelatin: Liquefaction. At 50° C. a gray- ish ring is produced and soluble pigment is formed. At 28° C. growth, with no soluble pigment. Synthetic agar: Poor growth at 28° C, deep gray, with but little aerial mycelium. At 50° C, growth dark to violet, with gray to lavender aerial mycelium and soluble brown pigment. Milk: Proteolysis. Potato: Abundant, dark colored growth, no aerial mycelium, or few white patches, dark soluble pigment. Starch is hydrolyzed. Temperature relations: Good growth at 50° and 60° C. Will grow at 65° C. Faint growth at 28° C. Aerobic. Distinctive characters: This species is distinguished from Streptomyces thermo- philus by the brown-colored aerial mycelium on synthetic media, spiral-shaped hyphae and ability to grow readily at 65° C. Source: Unknown. Habitat: Found in soils and composts. 117. Streptomyces casei (Bernstein and Morton, 1934) Waksman, 1953. (Actino- myces casei Bernstein and Morton, Jour. Bact., 27, 1934, 625; Waksman, in Waksman and Lechevalier, Actinomycetes and Their Antibiotics, Baltimore, 1953, 103.) ca'se.i. L. mas. n. caseus cheese; L. gen. noun casei of cheese. Vegetative growth: Colorless to white. Aerial mycelium: White, 0.5 to 0.7 mi- cron; no spirals. Gelatin: Complete liquefaction. Milk: Coagulated and peptonized. Starch is not hydrolyzed. Nitrates not produced from nitrates. Optimum temperature, between 40° and 60° C. Highly resistant to higher tempera- tures and to disinfectants. Thermal death point, 100°C. Relationships to other species: Krassil- nikov places this organism in the same group with Actinomyces invulnerabilis Acosta and Rossi (Cent. f. Bakt., 14, 1893, 14), the lat- ter being even more resistant to high tem- peratures and to disinfectants. Source: Isolated from pasteurized cheese. Habitat: Found in cheese so far as known. 118. Streptomyces clavifer (Millard and Burr, 1926) Waksman, 1953. (Actino- myces clavifer Millard and Burr, Ann. Appl. Biol., 13, 1926, 601; Waksman, in Waksman and Lechevalier, Actinomycetes and Their Antibiotics, Baltimore, 1953, 103.) cla'vi.fer. L. adj. clavifer club-bearing. Vegetative growth: Yellow to yellow- orange. Soluble yellow-brown pigment. Aerial mycelium: Sporophores long, straight, some terminating in club-shaped structures. Spores cylindrical, 1.0 by 1.5 microns. Gelatin: Gray to buff growth. White aerial mycelium. Soluble, yellow to reddish yellow pigment. Liquefaction. Synthetic sucrose agar: Gray to brick- red growth. Aerial mycelium white, sprinkled with light cinnamon-drab. Yel- lowish to brown soluble pigment. Synthetic glucose agar: Gray to brown
