142 



THE ACTINOMYCETES, Vol. I 



substituted neomycin was formed. The addi- 

 tion of zinc, even as low as 1 part per mil- 

 lion to media, resulted in antibiotic produc- 

 tion even in distilled water media. Iron, 

 manganese, copper, aluminum, calcium, and 

 magnesium, had no such effect. Lechevalier 

 was able to show a reciuirement for traces of 

 potassium, magnesium, iron, and calcium for 

 optimum neomycin production in media con- 

 taining glutamic acid and glucose. 



Dulmage also reported that in a synthetic 

 medium containing glutamic acid and glu- 

 cose to which metal salts were added, it was 

 necessary to have potassium, magnesium, 

 iron, zinc, and calcium for both growth and 

 neomycin production. When glutamic acid 

 was used as the only source of carbon and 

 nitrogen and the medium treated with 8- 

 hydroxyquinoline or ethylenediaminetetra- 

 acetic acid to render it metal-deficient, a re- 

 quirement for iron, calcium, magnesium, and 

 zinc for neomycin production by S. fradiae 

 was reported by Mohan and Nickerson. 

 These investigators were able to show a re- 

 quirement for calcium and magnesium for 

 growth, about a 50 per cent decrease in 

 growth when iron was omitted, and no effect 

 on growth when zinc was omitted from the 

 medium. 



Acker and Lechevalier made a study of 

 some nutritional requirements of S. griseus 

 for growth and candicidin production. A 

 synthetic medium was used; it was made 

 metal-deficient by calcium carbonate co- 

 precipitation. Essential requirements for 

 potassium, magnesium, iron, and zinc were 

 demonstrated. No effect of manganese on 

 either growth or antibiotic production was 

 obtained. 



In a study of the role of iron for the pro- 

 duction of grisein by S. griseus, liejniolds 

 and Waksman demonstrated that as the 

 concentrations of iron were increased, gris- 

 ein activity increased logarithn\ically. This 

 was due to the fact that ii-on is a part of the 

 grisein molecule. When iron was added to a 



solution of grisein in concentrations of 4 

 gm/1 as ferrous sulfate, partial inactivation 

 of the antibiotic resulted. Complete inacti- 

 \'ation of grisein occurred when 25 gm of 

 ferrous sulfate were added per liter of gris- 

 ein solution. Iron appeared thus to play a 

 (|uantitative role. Zinc had no effect on 

 grisein production. 



Kelner and Morton reported that iron has 

 a similar effect on the production of actin- 

 orubin. In a trypt one-glucose medium sup- 

 plemented with mineral salts, ferrous sulfate 

 added in concentrations of 5 mg/1 resulted 

 in increased antibiotic production, whereas 

 concentrations of 20 mg or more caused a 

 decrease in yield. 



In various other studies the production of 

 antimicrobial activity by three strains of 

 streptomj^cetes was foimd to be influenced 

 by manganese, zinc, iron, and copper. Con- 

 centrations lower than 2 mg/l were ineffec- 

 tive. Copper was inhibitory at a concentra- 

 tion of 10 mg/1. A complex medium was used 

 in these investigations. 



The addition of different concentrations of 

 sea water to a glucose-peptone-yeast-extract 

 medium resulted in an increase in soil iso- 

 lates (Jann et al.). Two streptomyces cul- 

 tures gave increased antibiotic production 

 on addition of sodium, potassium, calcium, 

 and magnesium as chlorides, sulfates, or 

 nitrates. With a third culture all of the above 

 metals, especially calcium caused an increase 

 in production of antibiotic. In the case of a 

 fourth culture, only calcium and sea salts 

 gave an increase in antibiotic yield. 



The importance of cobalt in the produc- 

 tion of A'itamin B12 is due to the presence of 

 this metal in the vitamin molecule. The need 

 for cobalt was demonstrated before the 

 structure of this A'itamin was known. Hend- 

 lin and linger found that cobalt became a 

 limiting factor for \-itamin pi'oduction l)y S. 

 griseus, e\'en in a complex medium. Cobalt, 

 added as Co(\03)..-6H20, caused a 3-fold 

 increase in vitamin B12 production, compared 



