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THE ACTINOMYCETES, Vol. II 



such forms as A. viridis, A. albidoflavus, and 

 .4. alboflavus, which definitely belong to 

 other groups. 



In his morphological study of the actino- 

 mycetes, Duche recognized five types of 

 sporulation, none of which was used for 

 systematic purposes. The relationship of 

 aerial hyphae, spirals, and spores was noi 

 sufficiently emphasized. Duche stated that 

 colonies may also originate from arthro- 

 spores, implying thereby that any mycelial 

 fragments will reproduce and multiply in 

 the culture. He spoke, however, of "mono- 

 sporic" colonies, although he used the 

 method of successive dilutions and not that 

 of single-spore isolation. He documented 

 the various interpretations of the species 

 A. albus, stating at first that the description 

 of Waksman "ne correspond pas tout a fait 

 aux type albus de Gasperini, Rossi-Doria 

 et Krainsky." On comparing his own cul- 

 ture with the preceding ones, he stated, 

 "L'espece de Waksman and Curtis semble 

 posseder toutes les proprietes de celle de 

 Krainsky. . . . Notre espeee resemble aux 

 deux precedentes." Baldacci concluded that 

 the work of Duche, after trying to prove the 

 diversity of the various interpretations in 

 the literature, had not attained its purpose 

 of establishing what the species A. albus 

 should be. 



In proposing the genus Streptomyces in 

 1943, Waksman and Henrici stated: "We 

 have selected as the type species of this 

 newly named genus, Streptomyces albus 

 (Rossi-Doria emend. Krainsky) comb. nov. 

 This species was formerly known as Actino- 

 myces albus Krainsky and first described as 

 Streptothrix alba Rossi-Doria. This is one 

 of the commonest and best known species 

 of the group, and, although it may later be 

 subdivided into further species, it is at 

 present as definite as any other. It has been 

 recently studied intensively by Duche ( L934) 

 and by Baldacci (1939). It is colorless, with 

 white aerial mycelium, forming ovoidal 



spores in coiled chains on lateral branches 

 of the aerial hyphae. It is proteolytic, lique- 

 fying gelatin and peptonizing milk with the 

 production of an alkaline reaction in the 

 latter. It does not produce any soluble pig- 

 ment either on an organic or synthetic me- 

 dium, but does produce a characteristic 

 earthy or musty odor." 



Pridham and Lyons (1960) have recently 

 made a comprehensive analysis of the pres- 

 ent status of Streptomyces albus. Their study 

 was based upon a detailed examination of 

 55 cultures collected from various sources. 

 They came to the conclusion that "there 

 has existed since about 1916, two entirely 

 different concepts with regard to the nature 

 of Actinomyces (Streptomyces) albus. One 

 concept centers around strains with the 

 following characteristics: flexuous fruiting 

 bodies, colors of aerial mycelium in tints 

 and shades of olive-buff (yellowish-gray or 

 tan) ; nonchromogenicity (inability to form 

 brown, deep brown, or black diffusible pig- 

 ments in organic substrates); and marked 

 abundance in nature" (these strains are now 

 considered as comprising members of the 

 Griseus group). "The other concept con- 

 cerns strains that are characterized by coiled 

 or spiralled fruiting bodies with catenulate 

 ovoidal spores; by aerial mycelium colors 

 generally interpreted as eretaceus (chalk- 

 white, often with faint tinges of pink); by 

 nonchromogenicity (inability to form brown, 

 deep brown, or black diffusible pigments in 

 organic substrata); and by their relative 

 rareness in nature" (these strains are now 

 considered as Albus group proper). 



Morphologic Characters 



Various methods were used in the study 

 of the morphology of S. albus. Baldacci 

 observed two types of mycelium. One was 

 hyaline, not less than 1 m in diameter, rami- 

 fying more or less abundantly, and having 

 an undulated appearance. The ramification 

 starts perpendicularly from the point of 



