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THE ACTINOMYCETES, Vol. I 



replaced by zinc or iron. Growth of S. scabies 

 was inhibited by ahuninum ions in concen- 

 trations of 20 or more parts per million 

 (Gries) . This inhibition could not be reversed 

 by the addition of magnesium. 



The addition of metals to the medium 

 also influences greatly pigment production. 

 This is true of ferroverdin, a green iron- 

 containing pigment produced by a strepto- 

 myces. Zinc sulfate concentrations of 0.001 

 per cent increase the rate of pigment forma- 

 tion in strains of red-yellow-pigment -forming 

 streptomycetes (Chain et al.). Omission of 

 magnesium or calcium from the medium re- 

 duced the amount of diffusible pigment but 

 omission of zinc or iron did not have any 

 effect on pigment production by S. fradiae 

 (Mohan). 



Stapp and Spicher and Spicher observed 

 that soil extract, or ash of soil extract, added 

 to synthetic nutrient solutions, gave in- 

 creased growth of a group of streptomycetes 



(Fig. 68). The increase in growth was nearly 

 proportional to the amount of ash added. 

 The media were purified by various proce- 

 dures, including sulfide precipitation and use 

 of calcium carbonate and 8-hydroxyquino- 

 line. When added to the medium in certain 

 concentrations and combinations, various 

 metals also yielded increased growth over 

 metal-deficient controls. The most effective 

 metals and concentrations were: iron at 0.05 

 mg per 100, manganese at 0.0005 mg per 

 100, and zinc, copper, and molybdenum at 

 0.005 mg per 100. Combinations were more 

 effective than single additions, the most 

 effective being iron-zinc, iron-manganese- 

 zinc, and iron-manganese-zinc-molybdenum 

 (Fig. 69). 



Heim and Lechevalier used a chemically 

 defined medium made metal-deficient by 

 treatment with activated chromatographic 

 alumina. The effect of iron, zinc, manganese 

 and calcium on the growth of eight strepto 



60 



§40 



8 



10 



2 4 6 



DAYS 

 Figure 69. Effect on streptomyces mycelial growth produced by various soil extracts: 1. field soil 2 

 compost soil, 3. field soil, ash of extract, 4. compost soil, ash of extract, 5. control (Reproduced from 

 Spicher, G. Zentr. Bakteriol., Abt. 2, 108: 580, 1955). 



