94 



NATURE, FORMATION, AND ACTIVITIES 



Ps. flnorescens; no accelerating effect of 

 chloramphenicol was observed (Katagiri 

 daL,19G0a). 



Evidence has recently been presented 

 (Anand and Davis, 1960) which indicates 

 the possibility that streptomycin is lethal to 

 sensitive cells because of interference with 

 cell membrane synthesis. This results in 

 drastic changes in the selective permeability 

 of the membrane, with attendant leakage of 

 important constituents such as nucleotides 

 from the cell to the outside. Inward permea- 

 bility is also affected. Here again, however, 

 one must be absolutely certain that the 

 effects observed are primary effects of the 

 antibiotic and not due to defects associated 

 with dead and dying cells. Hurwitz and 

 Rosano (1960), basing their results upon the 

 observation that chloramphenicol inhibits 

 killing by streptomycin when l)oth drugs 

 are added simultaneously, suggested that a 

 streptomycin-induced specific protein syn- 

 thesis precedes killing of the cells by strep- 

 tomycin. The reverse of this is that cells 

 lacking the potential for this induced protein 

 synthesis cannot be killed by this antibiotic. 

 The latter type cells presumably would in- 

 clude both host cells and streptomycin- 

 resistant bacterial mutants. 



By using radioactive amino acids for the 

 aerobic growth of M. tuberculosis (BCG), 

 Stachiewicz and Quastel (1959) demon- 

 strated that glycine and serine showed dis- 

 tribution of radioactivity in a large number 

 of amino acids of the microbial protein; on 

 the other hand, the use of radioactive alanine 

 and valine resulted in a protein in which 

 only these two amino acids were radioactive. 

 The effect of dihydrostreptomycin, in con- 

 centrations at which it exerts inhibitive 

 effects, upon the aerobic growth of M. 

 tuberculosis (BCG) consists in the inhibition 

 of protein synthesis. Xo effect was obtained 

 on labelled amino acid incorporation in E. 

 coli, but there was an effect in M. phlei 

 (see also Erdos and Ullmann, 1959). 



According to Erdos et al. (1960), strepto- 

 mycin inhibits the incorporation of tyrosine 

 into proteins of a sensitive strain of a sapro- 

 phytic Mycobacterium; on the other hand, 

 the incorporation of tyrosine into resistant 

 strains, as well as in a somewhat dependent 

 strain, w^as increased by the antibiotic. RNA 

 synthesis, either in resistant or sensitive 

 strains, was not influenced by streptomycin. 

 The antibiotic was said to inhibit transport 

 of amino acids from RXA to proteins. 



According to Shaw et al. (1960), manno- 

 sidostreptomycinase activity was inhibited 

 by the addition of Fe++, Ni++, Zn++, or 

 Cr''+ at the beginning of the fermentation. 

 The possible inhibition of mannosidostrep- 

 tomycinase synthesis by Fe++ was suggested. 

 Cii'^^ added after 144 hours to fermentation 

 l)roths containing 50 to 60 ppm of Fe+''" 

 rex'ersed the inhibition of enzyme activity 

 because of the presence of the ferrous ion. 

 Streptomycin production was reduced mark- 

 edly by Ni+"^ or Cu+"'", but was reduced only 

 slightly in the presence of both Xi++ and 

 Fe++. Further information on streptomy- 

 cinase is given by Sakakibara (1951) and on 

 the microbial degradation of streptomycin, 

 by Pramer and Starkey (1951) and Klein 

 and Pramer (1960). 



Henry and Hobby (1949) reported that 

 streptomycin activity varies directly with 

 concentration of the antibiotic, and inversely 

 with hydrogen ion concentration. Strepto- 

 mycin is both bacteriostatic and bactericidal, 

 depending on various factors. The bacterio- 

 static action of streptomycin appears after a 

 certain lag period. This action is antagonized 

 by most inorganic and organic salts and by 

 many sulfhydryl compounds. Streptomycin 

 was believed to inhibit the metabolism of 

 carbohydrates, ribonucleic acid, benzoic 

 acid, and amino acids. It was suggested that 

 the process of cell division or the synthesis 

 of protoplasm is blocked by interference by 

 streptomycin wdth one or more enzyme 

 systems essential to these functions. Han- 



