MlM.KAl. Mi:i'.\U()|.ISM WD 1 ;i'l"i:( "I' Ol" SAI/I'S ON CHoWni 



only coppci' yielded ;iii iiicic-ise in sti'e|)l()- 

 niNciii production. M;in,i;;inese ;ind zinc, 

 liowexcr, e;iused ,i decfense in ;int il)iol ic t'or- 

 n\;it ion (Tahle 'M)). 



I'sin^- a basal nieiliiun containing j!;luc()so 

 in nutrient l)r()tli, WooilrulT touiul increased 

 streptomycin production in surface cultures 

 of N. fin'sciifi to which sodium chlorid(\ fer- 

 rous sulfate, and zinc sulfate were added. 

 Maximum production was affected by the 

 latio of the supplements and th(> soiu'ce of 

 the \vat(M'. Zinc alone resulted in rapid jjel- 

 licle formation hut decr(>ased sti-eptomycin 

 pi'oduction, wliereas the addition of iron 

 caused a decrease in a;ro\vth hut an inci-ease 

 in antibiotic production. 



Streptomycin production by S. hiLinicnsis 

 was atfectcd differently, as shown by Johns- 

 tone and Waksman. The addition of ferrous 

 sulfate had no effect, but the yield of the 

 antibiotic was increased by the addition of 

 zinc sulfate to a medium containing meat 

 extract, peptone, ghicose, sodium chloride, 

 and taj) water. When both zinc and iron 

 were added at the same time, no noticeable 

 effect was obtained. Changes in sodium 

 chloride concentration also influenced an- 

 tibiotic production, the most effective 

 concentration being 1 per cent. By adding 

 sodium chloride to a complex medium con- 

 taining soybean meal. Rake and Donox'ick 

 ol)tained increased streptomycin production 

 by aS. grificus. Eiser and McFarlane found 

 that complex media with and without so- 

 (hum chloride supported the same amount 

 of growth on a dry weight basis, with no 

 difference in the residual glucose, ammonia, 

 or amino nitrogen. In the absence of sodium 

 chloride, streptomycin accumulated in the 

 mycelium, whereas in its presence the strep- 

 tomycin diffused more rapidly into the cul- 

 ture medium. Since the cation and anion 

 could b(> replaced by other closely related 

 ions in the Hofmeister lyotropic series, still 

 yielding similar results, the authors asciibed 



'I'Ain.K ;i() 



Kjffivt of imldl.'i on the {/loirlli, fitrcploini/cia 



production, and pH o/S. gri.seus (SpiLsbury) 



the results to the effects on membrane per- 

 meability rather than to osmosis. 



The concentration of iron is an important 

 factor. Rao reported a o.O-fold increase in 

 streptomycin production as a result of the 

 addition of iron to the medium. Asai et al. 

 studied growth and streptomycin production 

 in a complex, iron-rich medium, and found 

 that both were inhilnted at iron concentra- 

 tions greater than 0.0J5 per cent w/v. They 

 attributed the inhibition to a coUoid-chemi- 

 c;d phenomenon in which an iron gel covered 

 the mycelium, with the result that the organ- 

 ism was unable to take up nutrients or oxy- 

 gen from th(> medimn. 



The production of other antibiotics is also 

 affected by the presence of metal ions. Le- 

 che\'alier found that no neomycin was pro- 

 duced by *S'. fradiae in a medium containing 

 peptone, beef extract, glucose, sodium chlo- 

 ride, and distilled watei'. \Mien tap water was 



