Stimulation of Growth of Dcsulfovibrio desulfuricans 447 



Table 3, indicate that the growth of this microorganism did not 

 take place by deleting arginine, lysine, phenylalanine, serine, 

 threonine, leucine, isoleucine, valine, glutamic acid, aspartic 

 acid, or alanine from the complete medium. By omitting cystine 

 or proline, the growth was drastically reduced. Omission of each 

 of the remaining five amino acids, however, had little effect on 

 the growth. 



From these results it is considered that the first mentioned 

 eleven amino acids were indispensable to this microorganism, 

 and that cystine and proline were significantly stimulating. To 

 confirm this, we observed next the growth of the organism in a 

 defined medium containing ATP and the above thirteen amino 

 acids, in comparison with that in the media having somewhat 

 reduced compositions in amino acids from the above (Table 4). 



As shown in this table, the medium containing the thirteen 

 amino acids supported the normal growth which was similar to 

 that in the complete medium containing all eighteen amino 

 acids. When cystine and proline or cystine, proline, arginine and 

 glutamic acid, which were found in the preceding experiment 

 to exhibit relatively low activity as compared with the others, 

 were omitted from these thirteen amino acids, the growth ob- 

 tained was about three quarters and one-fifth of the normal 

 respectively. 



From these data it was confirmed that the thirteen amino 



TABLE 4 



Growth of D. Desulfuricans (Maizuru 1) in Chemically Defined 

 Media Containing Amino Acids in Different Compositions 



Amino Acid Added**** Growth, O.D. at 610 mfi 



All 18 amino acids 0.40 



13 amino acids (Arg, Lys, Phe, Scr, Thr, Leu, 



Isoleu, Val, Glu, Asp, Ala, CyS, and Pro) 0.37 



11 amino acids (Arg, Lys, Phc, Ser, Thr, Leu, 



Isoleu, Val, Glu, Asp, and Ala) 0.30 



9 amino acids (Lys, Phe, Ser, Thr, Leu, 



Isoleu, Val, Asp, and Ala) 0.07 



****Basal medium was composed of minerals, lactate, ascorbic acid and ATP. 



