THERMOPHILIC A.CTINOMYCETES 



303 



culture in the same group with .1. invul- 

 nerabilis (Acosta and Rossi) Berestnew, 

 1897, the latter said to be even more re- 

 sistant to high temperatures and to disin- 

 fectants. 



2. Streptomyces rectus Henssen, L957 

 (Henssen, A. Arch. Mikrobiol. 26: 373 414, 

 L957). 



Not .1 . rectus Krassilnikov. 



Synonym : Streptomyces thermophilus. 



Morphology: Sporophores straight, 36 to 

 60 fi long. Spores round or oval, 0.9 to 1 .2 ii. 



Sucrose nitrate agar: Growth moderate. 

 No aerial mycelium. 



Glycerol-asparagine agar: Growth good. 

 Aerial mycelium moderate, white to light 

 gray. 



Meat-extract agar: Growth good. Aerial 

 mycelium light gray. Soluble pigment brown. 



Cellulose-dextrin agar: Growth more or 

 less heavy. Aerial mycelium white-gray. 



Potato: Growth colorless. Soluble pigment 

 In-own. 



Starch : Slow hydrolysis. 



Nitrate reduction: Positive. 



Milk: Coagulated; not peptonized in 9 

 days. 



Gelatin: Not liquefied (Waksman et al. 

 I L939) obtained liquefaction). 



Habitat: Fresh horse manure. 



Remarks: Thermotolerant mesophile. 

 Grows equally well under aerobic and an- 

 aerobic conditions. 



The name "thermophilus" for this species 

 was not recognized by Henssen (1957), since 

 it was first used by Berestnew (1897) for 

 another actinomycete, apparently also a 

 species of Streptomyces, which was distin- 

 guished from S. rectus by spiral-forming 

 chains of aerial spores, gray or dark green 

 aerial mycelium, and yellow to dark brown 

 colonies. Noack (1912) described an or- 

 ganism, under the name "thermophilus," 

 which produced a soluble red pigment . Miehe 

 (1907) and Schiitze (1908) also described 

 organisms under this name. 



.'!. Streptomyces thermodiastaticus (Bergey, 

 Mil!)) nov. comb. (Bergey, I). H. .1. Bac- 

 terid. 1: 301, 1919). 



.Morphology: Sporophores form spirals. 

 Spores spherical to oval, 0.9 by 0.7 or 0.8 ^. 



Synthetic agar: Growth colorless. Aerial 

 mycelium well developed, white. 



Potato: Growth brownish. Aerial myce- 

 lium light gray. 



( ielatin: Liquefaction slow. 



Milk: No coagulation; no peptonization. 



Starch: Strong hydrolysis. 



Cellulose: Growth good. 



Nitrate reduction: Positive. 



Sucrose: Inverted. 



Temperature: Optimum, 65°C. 



Habitat: Mouth of rabbit. Soil. 



4. Streptomyces thermofuscus (Waksman 

 et al., 1939) nov. com!). (Waksman, S A., 

 Umbreit, W. W., and Cordon, T. C. Soil Sci. 

 47: 49, 1939). 



Morphology: Aerial mycelium gives rise 

 to spiral-shaped sporophores; spores spher- 

 ical. 



Sucrose nitrate agar: At 28°C, growth 

 poor, deep gray, with but little aerial my- 

 celium. At 50°C, growth black to violet, 

 with gray to lavender aerial mycelium. Sol- 

 uble pigment brown. 



Potato: Growth abundant, brown-col- 

 ored. Aerial mycelium, none or a few white 

 patches. Soluble pigment black. 



Gelatin: Liquefied. At 50°C, a grayish 

 ring is produced and a soluble pigment is 

 formed. At 28 °C, there is growth withotit 

 any soluble pigment. 



Milk: Peptonized. 



Starch: Hydrolysis. 



Temperature: Good growth at 50 and 

 ()0°C. Will grow at 65°C. faint growth at 

 28°C. 



Habitat : Horse manure. 



Remarks: This species is characterized by 

 brown-colored aerial mycelium on synthetic 

 media, spiral-shaped sporophores, and abil- 

 ity to grow readily at i\r>°C. 



