Waksman — 98 — Actinomycetes 



Thermophilic actinomycetes in culture can be isolated by one of 

 several simple procedures. Tsiklinsky inoculated sterile potatoes with 

 compost material and incubated them at 53-55 °C. After 16 hours' 

 incubation, plates were prepared and incubated at the same tempera- 

 ture. Two cultures of actinomycetes were thus obtained, one of which 

 produced chains of spores and may, therefore, be considered as a spe- 

 cies of Streftomyces, and the other produced round or ovoid spores at 

 the end of side branches, caused by the swelling of the tips, thus rep- 

 resenting a true Micromonospora. The second organism was believed 

 to be widely distributed in nature and was designated as Thermoactino- 

 myces vulgaris. It grew at 48-68°C., with an optimum at 57°C. At 

 37 °C. or at lower temperatures, it remained inert, but became active 

 within 24 hours when incubated at 56-57° C. The spores of this or- 

 ganism were not destroyed at 100°C. even after 20 minutes. The 

 organism also resisted the action of disinfectants and grew readily on 

 most of the ordinary media. It was strongly proteolytic but not amylo- 

 lytic. The Streptomyces form, designated Thermoactinoniyces II, was 

 less proteolytic, and the spores were less resistant to heat. 



Gilbert (135) isolated several thermophilic actinomycetes from 

 various soils. He included them under one species as A. ihermofhi- 

 lus. The organisms produced a lichnoid growth, with white aerial 

 mycelium which later became gray. The optimum temperature for 

 growth was 55°, with a maximum at 60° C. Most strains ceased to 

 grow even at 45°, although some could be adapted to grow on agar 

 media at 37° and even lower temperatures. Gelatin was slowly lique- 

 fied. 



MiEHE (295) looked upon the thermophilic actinomycetes as the 

 characteristic organisms inhabiting the decomposing masses of plant 

 material under high-temperature conditions. These hot composts, 

 rather than the soil, were believed to be the natural substrates of the 

 thermophilic organisms. The spores lost their vitality rapidly, espe- 

 cially on agar media, but survived on hay particles. One organism, desig- 

 nated as A. thermophihis Berestneff, grew well at 40°— 50° C, more 

 slowly at 30°, and not at all at 25° and 60°C. The manner of spore 

 formation of this organism suggests that it was also a member of the 

 Micromonospora group. Miehe reported, however, that some of the 

 thermophilic actinomycetes produced spores in a manner similar to 

 that described bv Gilbert. Schutze (399) reported the presence 

 in decomposing clover hay of representatives of two types of thermo- 

 philic actinomycetes, one of which was designated as A. therniophiliis 

 Berestneff and the other as A. monosponis Lehmann and Schiitze. 

 The latter may be definitely considered a member of the Micromono- 

 spora group. 



