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THE ACTINOMYCETES, Vol. II 



Table 15 

 Utilization of carbon sources by a group of closely related 

 Streptomyces species (Corbaz et al., 1957) 



+ = good growth; (+) = weak growth, questionable carbon utilization; (— ) = very weak growth; 

 = no growth. 



V. Series I iridis 



Characteristic Properties 



a. Sporophores straight or spiral-shaped. 



b. Growth at first colorless, becoming 

 green to dark green. Aerial mycelium white 

 to gray to light green to light blue. 



c. Melanin-negative. 



d. Soluble pigment absent or greenish. 

 The species included in this series show 



considerable overlapping with the species in- 

 cluded in the chromogenic series, such as S. 

 viridochromogenes (syn. A. viridis (Lom- 

 bardo-Pellegrino) Baldacci) . 



Various other organisms that might be 

 included in this series have been described. 

 It is sufficient to list S. alboviridis, S. griseo- 

 viridis, and S. dassonvillei. 



The following organisms may be included 

 in the Viridis series: S. viridis, S. prasinus, 

 S. hirsutus and »S r . prasinopilous. 



Several forms described by Gause et <d. 

 (1957) could be included in this series, 

 notably A. malachiticus and A. olivaceoviri- 

 dis. 



VI. Series Violuceoruber 



Characteristic Properties 



a. Sporophores produce spirals. Spores 

 spherical to oval. Surface of spores smooth. 



b. Substrate growth colorless, becoming 



red, later blue. Aerial mycelium white to 

 gray with bluish tinge. 



c. Melanin-negative. Soluble red pigment 

 in acid media, changing to blue in alkaline. 



A number of organisms belonging to the 

 genus Streptomyces are able to produce a 

 blue pigment when grown on certain media 

 (Tables Hi, 17). This pigment is either re- 

 tained in the substrate mycelium or is readily 

 dissolved in the medium; it is frequently ac- 

 companied by a dark chromogenic pigment. 

 The color of the pigment ranges, therefore, 

 from light blue to dark blue or violet, and to 

 almost black. The soluble pigment fre- 

 quently changes in color with a change in 

 reaction of medium, from red at an acid 

 reaction to blue at an alkaline reaction. Be- 

 cause of this change in the color of the pig- 

 ment, various names, indicating the red and 

 blue color combinations, have been used to 

 describe the species, such as ^violaceus" 

 "violaceoruber," "violaceoniger," "tricolor" 

 and "pluricolor.'" The species capable of 

 producing blue pigments are divided here 

 into two distinct subgroups: S. violaceoruber 

 and S. violaceoniger. The first comprises the 

 forms that produce a litmus-like pigment, 

 changing from red in acid media to blue in 

 alkaline; the second includes those forms 

 that produce violet to dark blue to almost 

 violet-black pigments on synthetic and or- 

 ganic media. 



