PYRIDOXINE 



was found less effective than DL-alanine as a substitute for pyridoxine.^' 

 This is confirmed by the fact that pyridoxine was present in neghgible 

 amounts in Lactobacilli grown on a pyridoxine-free medium containing 

 D-alanine.^'" It was, in fact, found that both L. helveticus and S. 

 faecalis accumulated D-alanine when grown on media containing either 

 D-alanine or pyridoxine, and it seems more likely therefore that 

 pyridoxine is necessary for the synthesis of D-alanine, as might be 

 expected from other evidence (page 333). Not all species of lactic 

 acid bacteria require pyridoxine, some being able to synthesise it.^^ 

 Pyridoxine was essential for the growth of Bacterium acetylcholini ^^ and 

 Streptobacterium plantarum,^^ however, and also for Clostridium tetani.^'^ 

 The amounts of pyridoxine in the cells of the five bacteria, Aero- 

 bacter aerogenes, Serratia marcescens, Pseudomonas fluorescens, Proteus 

 vulgaris and Clostridium butylicum were estimated by H. Mcllwain ^^ 

 to be equivalent to between 2100 and 6600 molecules per cell and the 

 rates of synthesis at between i and 5 molecules per cell per second. 



Protozoa 



Tetrahymena geleii required 0-45 /xg. per ml. of pyridoxine when the 

 medium was sterilised by filtration or 0-25 /xg. per ml. when sterilised 

 by autoclaving, the activity of the pyridoxine being increased when 

 heated with amino acids. ^^ Pyridoxal and pyridoxamine were 100 

 to 500 times more effective. 



References to Section 16 



1. A. S. Schultz, L. Atkin and C. N. Frey, /. Amer. Chem. Soc, 



1939. 61, 193 1 ; A. S. Schultz and L. Atkin, Arch. Biochem., 

 1947. 14, 369. 



2. R. E. Eakin and R. J. Williams, /. Amer. Chem. Soc, 1939, 61, 



1932. 



3. P. R. Burkholder, Amer. J. Bat., 1943, 30, 206 ; P. R. Burkholder 



and D. Moyer, Bull. Torrey Bot. Club, 1943, 70, 372 ; /. Bad., 

 1944. 48, 385. 



4. C. Marchant, Canad. J. Res., 1942, 20B, 21. 



5. W. J. Robbins and R. Ma, Bull. Torrey Bot. Club, 1942, 69, 342; 



Proc. Nat. Acad. Sci., 1943, 29, 172. 



6. P. R. Burkholder and I. McVeigh, Science, 1942, 95, 127. 



7. W. H. Schopfer, Arch. Julius Klaus-Stiftung, 1945. 20, 27. 



8. N. Fries, Naturwiss., 1942, 30, 685 ; Symbolae Botan. Upsaliensis, 



1943, 7, No. 2. 



9. W. H. Schopfer, Experientia, 1945, 1, 183. 



10. J. L. Stokes, J. W. Foster and C. R. Woodward, Arch. Biochem., 



1943. 2. 235. 



11. R. C. Wooster and V. H. Cheldelin, ibid., 1945, 8, 311. 



340 



