VITAMIN Bi2 (ERYTHROTIN) 



a component of the virus, since there was not sufficient of the vitamin 

 present to provide one molecule per virus particle.' 



Synthesis of Vitamin B12 by Micro-organisms 



Vitamin B^g is synthesised by the mould, Streptomyces griseus, and 

 vitamin B^^h t>y S. aureofaciens (page 531). It is also synthesised, 

 apparently in the form of a complex inactive in human pernicious 

 anaemia but active in chicks, by a non-motile, rod-shaped organism 

 isolated from hen droppings.^ It is probably synthesised by bacteria 

 in the rumen of sheep ^ and, as might be expected, the synthesis is 

 promoted by the ingestion of cobalt.^ ^ 



The presence of a cobalt-containing substance similar to vitamin 

 B12 in cow-dung ^^ is presumably due to bacterial synthesis in the 

 rumen or intestine of cattle, and it has also been suggested that 

 vitamin B^g may be synthesised by the intestinal flora in humans, and 

 even in patients suffering from pernicious anaemia (page 539). 



References to Section 6 



1. L. D. Wright, H. R. Skeggs and J. W. Huff, /. Biol, Chem., 1948, 



175, 457 ; W. Shive, J. M. Ravel and W. M. Harding, ibid., 

 1948, 175, 991. 



2. I. Z. Roberts, R. B. Roberts and P. H. Abelson, /. Bad., 1949, 



58, 709- 



3. A. D. Welch and M. F. Wilson, Arch. Biochem., 1949, 22, 486. 



4. J. L. Ternberg and R. E. Eakin, /. Amer. Chem. Soc, 1949, 71, 



3858. 



5. M. H. Wright, Science, 1949, 110, 257 ; H. E. Sauberlich, Arch. 



Biochem., 1949, 24, 224. 



6. S. H. Hutner, L. Provasoli, E. L. R. Stokstad, C. E. Hoffmann, 



M. Belt, A. L. Franklin and T. H. Jukes, Proc. Soc. Exp. Biol. 

 Med., 1949, 70, 118. 



7. R. B. Roberts and M. Sands, /. Bad., 1949, 58, 710. 



8. E. L. R. Stokstad, A. C. Page, J. V. Pierce, A. L. Franklin, T. H. 



Jukes, R. W. Heinle, M. Epstein and A. D. Welch, /. Lah. Clin. 

 Med., 1948, 33, 860. 



9. P. H. Abelson and H. H. Darby, Science, 1949, HO, 566. 



10. H. R. Marston and H. J. Lee, Nature, 1949, 164, 529. 



11. K. Hausmann, Lancet, 1949, 2, 962. 



544 



