122 



THE ACTINOMYCETES, Vol. II 



Concentric ring formation may be observed 

 in smaller colonies, as described by Rossi- 

 Doria. The cultures produce the character- 

 istic moldy or soil odor. 



On synthetic agar, the initial develop- 

 ment of the culture is characterized by a 

 dusty or powdery white, dry growth, form- 

 ing furrows or concentric rings. The sub- 

 strate mycelium is formed in a thin, scarcely 

 visible layer over the agar. The colony does 

 not assume a vigorous aspect. The white 

 aerial mycelium appears late. Pigmentation 

 of the agar is seldom observed, except for 

 a few strains that show feeble chromogenesis 

 in this medium. 



On potato, the development is rapid, with 

 small, partly confluent colonies or in the 

 form of extended membranous growth that 

 becomes covered with white aerial myce- 

 lium. 



Biochemical Properties 



Temperature: Optimum 24-28° (24- 

 44°)C. 



Gelatin: Liquefied. 



Starch: Diastatic action variable. 



Sucrose: Inverted. 



Nitrate: Reduced to nitrite. 



Antagonistic properties: The organisms 

 belonging to the S. albus group are usually 

 weak antagonists. Some cultures possess 

 activity against gram-positive bacteria. 



Species 



Krassilnikov (1949) included 19 species 

 in the Albus series. He used a combination 

 of different criteria for their separation and 

 identification. For separation of the cul- 

 tures, he considered the odor produced as 

 the major criterion, which is rather unrelia- 

 ble. Use of this criterion is largely responsi- 

 ble for the inclusion, in this group of species, 

 of forms designated as aromaticus, odoratus, 

 odorifer, putrificus, etc. Krassilnikov also 

 considered, for identification purposes, the 

 shades of white in the aerial mycelium, tem- 



perature relation, proteolytic and antago- 

 nistic properties, the secretion of a brown 

 substance, growth in acid media, production 

 of ammonia and HjS, decomposition of 

 rubber, and formation of coremia. He in- 

 cluded in this group various thermophilic 

 and thermotolerant organisms. 



Cause et al. (1957) divided the Albus 

 series, on the basis of the color produced on 

 a complex organic medium, into three sub- 

 groups, comprising five species and one 

 variety: 



a. Medium not pigmented: ^4. candidus, 

 A. candidus var. alboroseus, and A. 

 albidoflavus. 



b. Medium colored brown: A. longisporus 

 and A. mirabilis. 



c. Medium colored brownish: A. albo- 

 rubidus. 



The above characterization fails to recog- 

 nize some of the fundamental cultural prop- 

 ert ies of actinomycetes, namely, the produc- 

 tion of melanin pigments in protein media 

 and the structure of the sporophores. The 

 resulting subdivision of such a group into 

 subgroups thus loses all significance. Only 

 one of the above species (A. albidoflavus) is 

 found in Krassilnikov's "albus" series. 

 Kutzner (1956) reported that he had ob- 

 tained four strains of S. albus from different 

 institutions and found them to be identical. 



Baldacci placed in the Albus series the 

 following organisms, either because they 

 were considered as synonyms or because 

 they were believed to be closely related: 

 Actinomyces albus, A. acidophilus, A. alm- 

 quisti, A. beddardi, A. chromogenus, A. 

 erythreus, A. exfoliatus, A. farcinicus, A. 

 flocculus, A. gedanensis, A. gelaticus, A. 

 gougeroti, A. heimii, A. kimberi, A. lieskei, 

 A. listerii, A. malenconi, A. reticuli, A. soma- 

 liensis, A. sanninii, A. saprophytic us, A. 

 thermophilus, A. upcottii, A. willmorei; Clad- 

 othrix dichotoma, C. liquefaciens, ('. invul- 

 nerabilis, C, odorifera; Oospora doriae, 0. 

 alpha; Streptolhri.v alba, Str. Candida, Str. 



