360 RIBOFLAVIN 



The riboflavin content of the milk of cows and goats^ is many times the 

 amount in the feed, as the result of synthesis by organisms which inhabit 

 the rumen of these animals. 



Observations that the fecal contents of rats,^ fowls/ and man^- ^ may 

 have more riboflavin than the food ingested have stimulated research on 

 the nutritional usefulness of intestinal synthesis. It has been common labo- 

 ratory knowledge that coprophagia by rats must be avoided if nutritional 

 deficiencies are to be produced. Whether the riboflavin formed by micro- 

 organisms is absorbed from the lower intestinal tract in significant quan- 

 tities is not certain. Najjar et at} have reported that there was a rise in 

 urinary riboflavin after normal subjects were given enemas containing 20 

 mg. of riboflavin, but Everson et al.^ found no increase in urinary excretion 

 of riboflavin after administering 2 mg. by retention enema. The concept of 

 low utilization of the riboflavin of intestinal bacteria is supported by 

 studies^ indicating the relative non-availability of the vitamins in ingested 

 yeast. 



Although riboflavin is required as a growth factor for a large number of 

 microorganisms,^ most of them are able to synthesize more than their 

 requirement. Microbiological production of riboflavin by Clostridium 

 acetohutylicum has been promoted as a commercial source.^ There have 

 been reports on riboflavin production by the yeast Eremothecium ashhyii^^ 

 and by Candida guilliermondia}'^ • ^^ Certain molds (Ashhya gossypii) pro- 

 duce and excrete so much riboflavin that yellow crystals are formed about 

 the mycelium.^^ 



An investigation of riboflavin synthesis by the bacterial flora of the 

 human intestine has been made by Burkholder and McVeigh. ^^ The organ- 

 isms studied were Escherichia coli, Proteus vulgaris, Bacterium aerogenes, 

 Alcaligenes faecalis, Bacillus mesentericus, and Bacillus vulgatus. E. coli, 



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2 W. H. Griffith, J. Nutrition 10, 667 (1935). 



3 W. F. Lamoureux and R. S. Schumacher, Poultry Sci. 19, 418 (1940). 



^ V. A. Najjar, G. A. Johns, G. C. Medairy, G. Fleischmann, and L. E. Holt, Jr., J. 



Am. Med. Assoc. 126, 357 (1944). 

 s C. W.. Denko, W. E. Grundy, N. C. Wheeler, C. R. Henderson, G. H. Berryman, 



T. E. Friedemann, and J. B. Youmans, Arch. Biochem. 11, 109 (1946). 



6 G. Everson, E. Wheeler, H. Walker, and W. J. Coulfield, J. Nutrition 35, 209 

 (1948). 



7 H. T. Parsons, A. Williamson, and M. L. Johnson, /. Nutrition 29, 373 (1945). 



8 W. H. Peterson and M. S. Peterson, Bacteriol. Revs. 9, 49 (1945). 



9 C. F. Arzberger, U. S. Pat. 2,326,425 (Aug. 10, 1943). 



1" A. Raffy and M. Fontaine, Co7npt. rend. 201, 1005 (1937). 



'1 P. R. Burkholder, Proc. Natl. Acad. Sci. U. S. 29, 166 (1943). 



12 F. W. Tanner, C. Vojnovich, and J. M. Van Lanen, Science 101, ISO (1945). 



13 A. Raflfy, Compt. rend. soc. biol. 126, 875 (1937). 



" P. R. Burkholder and I. McVeigh, Proc. Natl. Acad. Sci. U. S. 28, 285 (1942). 



