CHAPTER 13 



Production of Pigments 



Among the most characteristic properties 

 of actinomycetes is their abihty to produce 

 a great variety of pigments, both on organic 

 and on synthetic media. This pigment-pro- 

 ducing capacity is so characteristic as to 

 serve for the naming of a large number of 

 the species, notably those belonging to the 

 genus Streptomyces. Very few of these pig- 

 ments are pure. Most of them are mixed, 

 with gradual transition from one color of 

 the rainbow to another. 



Conn and Conn emphasized the value of 

 pigmentation in classifying actinomycetes. 



Stapp isolated from various soils 477 cul- 

 tures of streptomyces. Their growth on 

 glycerol-asparagin agar gave the following 

 pigmentation: 31 per cent of the colonies 

 were gray in appearance; 19 per cent yellow 

 (cream to orange); 18 per cent brown; 17 

 per cent white; 8.4 per cent red; 4.2 per cent 

 blue; 1.3 per cent green; and 0.8 per cent 

 black. 



von Plotho (1948) divided the actinomy- 

 cetes into four large groups according to the 

 pigments produced: 1. red-yellow; 2. red- 

 blue; 3. red-brown; 4. colorless. Some of the 

 pigments possess indicator properties: at an 

 acid reaction, the red pigment predominates; 

 at an alkaline reaction, the second pigment 

 prevails. The colorless group have given the 

 greatest number of antibiotic-producing 

 strains. Members of the red-l^lue group pro- 

 duce strong pigments but weak antibiotics. 

 Members of the red-yellow group produce 

 both strong pigments and liighly active anti- 



biotics. The members of the red-brown group 

 produce neither true pigments nor active 

 antibiotics. 



Only very few of the pigments of actino- 

 mycetes have been studied in detail. Some 

 are soluble in water, others are soluble in 

 alkalies, and still others in organic solvents, 

 such as alcohol or chloroform (Table 48). 

 These pigments have been divided into three 

 groups: anthocyanins, carotenoids, and mela- 

 nins. The red-blue pigments of the actino- 

 mycetes belong to the first group; red-or- 

 ange-yellow pigments belong to the second; 

 the black and brown pigments belong to the 

 third. Some of the pigments are fluorescent, 

 and some change in color with a change in 

 reaction of medium. Some are intracellular; 

 others are exocellular and dissolve readily in 

 the medium. Some of the pigments are pro- 

 duced only on certain specific media, notably 

 synthetic media; others are produced on a 

 variety of media. In many cases, a change 

 in the composition of medium results in a 

 change in the natvu'e of the pigment. 



The pigments of actinomycetes are usually 

 described in terms of \'arious shades of blue, 

 violet, red, rose, yellow, green, brown, and 

 black. The shades of color are also frequently 

 indicated, as light gray, deep gray, mouse 

 gray. The pigments may be concentrated 

 either in the A'egetative myceliinn or in the 

 aerial mycelium and spores. 



The pigment-producing property of ac- 

 tinomycetes is variable, depending upon the 

 nature of the medium, the age of culture, 



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