146 



THE ACTINOMYCETES, Vol. I 



production. Mn could replace Mg in the 

 growth requirement, but only a Mn con- 

 centration of 10~- M allowed any chloram- 

 phenicol production. In a medium containing 

 optimum concentrations of Zn, Fe, and Mg, 

 the presence of the other microelements 

 studied, singly or in groups, had little effect 

 on growth or the production of the antibiotic. 



Metals are common contaminants of most 

 of the media used for the growth of actino- 

 mycetes. Complete removal of some metals, 

 such as calcium, copper, and iron, is virtu- 

 ally impossible. A positive reaction in any 

 medium indicates, however, a qualitative 

 effect of the particular metal on the particu- 

 lar reaction. More refined experiments are 

 required to explain the enzymatic basis for 

 the reactions observed. 



The effect of minor elements on the growth 

 and nutrition of actinomycetes has been 

 studied further by Perlman (1949), and by 

 numerous other investigators. Their effect 

 on antibiotic production was examined by 

 Sanchez-Marroquin and Arcimega. 



Effect of Salt Concentration 



As pointed out elsewhere, actinomycetes 

 have been reported to occur in sea water and 

 in sea bottoms. According to Kober, S. oligo- 

 carbophilus, grown in a 0.5 to 0.6 M NaCl so- 

 lution, produced fewer but larger colonies 

 than in XaCl-free solutions. Although 

 MgS04 is not essential for growth, it had a 

 favorable effect even in fairly high concen- 

 trations. Calcium was not essential for 

 growth, but its absence had an injurious 

 effect unless magnesium was present. Potas- 

 sium, in concentrations of 0.5 per cent KCl, 

 was injurious; this effect was neutralized by 

 high concentrations of MgSOi . S. oligocarbo- 

 philus is noticeably hallophilic^ and could tol- 

 erate 25 percent MgS()4 ■ THoO, butonly 5 per 

 cent NaCl. At 15 per cent MgS04-7H20 

 or at 3 per cent NaCl, the colonies gi-ew 

 well. 



Stapp has also shown that actinomycetes 

 can tolerate a high salt concentration. Many 

 strains were able to grow in a 10 per cent 

 concentration of KNO3 ; NaCl was tolerated 

 by some strains in a maximum 8 per cent 

 concentration, 6 per cent by others, and 

 only 1 per cent by still others; some strains 

 tolerated 30 per cent NaS04 and others only 

 2 per cent. Some strains were able to grow 

 in a 10 per cent concentration of MgS04 , 

 and one grew weakly even in a 50 per cent 

 concentration of the salt. 



Sodium thiosulfate was tolerated in 10 

 per cent concentration. KI and KBr were 

 tolerated in 5 per cent concentration; LiCl 

 only up to 0.5 per cent by one strain and 

 CsCl up to 0.1 per cent. SrCb permitted 

 the growth of some strains in 1 per cent 

 concentration. 



Some strains are resistant to salts usually 

 considered as toxic. 



In earlier studies on the growth of actino- 

 mycetes, Neukirch (1902) obser^'ed that S. 

 ochroleucus grew in broth containing 2 per 

 cent NaCl. Lachner-Sandoval (1898) re- 

 ported that good development of S. alhido- 

 flavus took place in a medium containing 16 

 per cent NaCl. The fact that actinomycetes 

 are found in salt-rich substrates, such as 

 curative muds (Rubentschik) and in the sea 

 close to shore, speaks for their adaptation to 

 salt-rich environments. Krassilnikov re- 

 ported on the ability of various actinomy- 

 cetes (Streptomyces, Nocardia) to grow well 

 in the presence of 10 per cent NaCl or 20 

 per cent Na2S04 . He noted that the major- 

 ity of actinomycetes are able to grow in 

 higher salt concentrations than bacteria. 

 This was true particularly of the pigmented 

 organisms. 



These results tend to suggest that the role 

 of metallic elements as integral parts of cell 

 systems and of catalytic processes of en- 

 zymes is of considerable importance. McFJ- 

 roy and Nason presented certain patterns 

 which appear to be e\-ol\ing from physico- 



