32. THE NUCLEIC ACIDS OF MICROORGANISMS 151 



corded that on the addition of vitamin B ]2 to the culture of Lactobacillus 

 leichmannii the cells synthesize 3-4 times more DXA than without the 

 vitamin. It should be noted that the authors calculated the DNA content 

 per dry weight and not per cell. It was shown recently that in the presence 

 of (8-2-thienylalanine the DNA content in the cells of E. coli, strain B, in- 

 creased twofold during 1 hour. 36 A 3-4 times increase of the DNA content 

 per cell under the influence of penicillin was found for Proteus vulgaris. 31 

 In the latter case, however, the question is complicated by the transition 

 of the microbe to the L-form, i.e., a certain type of variability. 



Interesting data based, by necessity, on calculation per dry weight and not. per 

 cell, were obtained by Demyanovskaya and Belozersky 38 in 1954. They failed to find 

 DNA at the early stages of growth of Streptomyces streptomycini, i.e., during 6-12 

 hours after the transfer of the inoculum into large fermenters, though the inoculum 

 had the usual DNA content (2-2.5%). These data were confirmed by Guberniyev el 

 a'. 39 on Streptomyces aureofaciens. However, the reinvestigation of this case under- 

 taken in our laboratory in collaboration with N. V. Shugayeva showed DNA to be 

 present, though its amount became very small in the first hours of mycelium growth, 

 namely 0.05-0.2% per dry weight. It was also shown that the DNA of this young my- 

 celium had the same composition as the DNA of the mycelium having a normal DNA 

 content. After the early period of mycelium growth, the DNA content in the ar;ti- 

 nomycetes returns to the normal level and then remains constant. 38 ' 39 Apparently, 

 analogous phenomena of a sharp fall of the DNA content during certain periods of 

 the early growth of mycelium may be observed in fungi. 40 ' 4 ° a 



2. Ribonucleic Acid 



Changes in RNA are responsible, mainly, for the general picture of the 

 nucleic acid dynamics revealed in the early studies. 3711 The decrease of 

 the RNA content in the course of growth during the logarithmic phase and 

 the transition from the logarithmic to the stationary phase was confirmed 

 in a number of investigations carried out on various species and strains of 

 microorganisms. 20 " 22 ' 24 ' 38 - 39 ' 4148 The RNA content in the cell appears to 



36 A. B. Pardee and L. S. Prestidge, Biochim. et Biophys. Acta 27, 412 (1958). 



37 M. V. Nermut and V. Drasil, Nature 181, 1740 (1958). 



38 N. S. Demyanovskaya and A. N. Belozersky, Biokhimiya 19, 688 (1954). 



39 M. A. Guberniyev, N. A. Ugoleva, and L. I. Torbochkina, Antibiotiki 1, 8 (1956). 



40 E. Hammarsten and H. Palmstierna, Acta Chem. Scand. 11, 1378 (1957). 



40a H. Venner, Abstr. 4th Intern. Congr. Biochem., Vienna No. 3-44, p. 36 (1958). 



41 A. N. Belozersky, V. B. Korchagin, and T. I. Smirnova, Doklady Akad. Nauk 

 S.S.S.R. 71, 89 (1950). 



42 C. A. Fish, I. Asimov, and B. S. Walker, Proc. Soc. Exptl. Biol. Med. 75, 774 (1950). 



43 W. H. Price, J. Gen. Physiol. 35, 741 (1952). 



44 H. E. Wade, J. Gen. Microbiol. 7, 24 (1952). 



45 H. Sato, Tohoku J. Exptl. Med. 60, 375 (1954). 



46 A. N. Belozersky, I. V. Asseeva, and A. F. Moroz, Doklady Akad. Nauk S.S.S.R. 

 109, 149 (1956). 



47 S. A. Popienenkova, Zhur. mikrobiol. epidemiol. im nunobiol. No. 1, 26 ( 1 9 ">6 ) . 



48 R. Vaamonde Fernandez and B. Regueiro Varela, Microbiol, espah. 10, 461 (1957). 



