588 BIOTIN 



Rats in which coprophagy has been prevented grew V^etter when Ijiotin 

 (and foHc acid) were added to the diet, whereas in control animals with 

 access to their own feces a dietary recjuirement for supplementary biotin 

 (and folic acid) was not demonstrable.^^ Finally, the addition of sulfa drugs, 

 such as succinylsulfathiazole, to rats kept on a purified semisynthetic diet 

 not only retarded growth but also produced symptoms strongly reminiscent 

 of egg white injury.'* -*' These latter manifestations may be relieved by 

 adding biotin to the diet. The biotin content of the liver is decreased in 

 rats when succinylsulfathiazole is added to the diet.-' All these observations 

 are in good accord with the assumption that biotin is synthesized by the 

 intestinal flora. 



Dietary carbohydrates may influence the fecal flora and indirectly the 

 intestinal synthesis of biotin.-'-' -^ This is promoted in chicks by added 

 dextrin but not by sucrose or lactose. Oats have an especially marked effect 

 on the bacterial synthesis of biotin.-^ 



If green plants are able to synthesize biotin, the synthesis must take 

 place in the leaves rather than in the roots. Root production is stimulated 

 by biotin in etiolated cuttings of pea roots,-* and under ordinary conditions 

 of plant growth the roots may depend for at least part of their biotin supply 

 on soil microorganisms. 



VII. Estimation 



PAUL CiVOHGV 



In natural food products and e\'en in concentrates, biotin is present only 

 in extremely small concentrations. Conseciuently its estimation depends 



» V. H. Harki, P. U. Dorse, R. A. Collins, K. B. Hart, and C. A. Klvehiem, ./. Xulri- 



tion 37, 443 (1949). 

 15 F. S. Daft, L. L. Ashburn, and W. II. Sebrell, Science 96, 321 (1942). 

 1" G. J. Martin, Pmc. Soc. Exptl. Biol. Med. 51, 353 (1952). 

 " E. Nielsen and C. A. Elvehjem, ./. Biol. Chem. 145, 713 (1942). 

 '8 F. W. Heumann, M. M. Kridor, and II. G. Day, Proc. Soc. E.rptl. Biol. Me, I. 52, 



257 (1943). 

 '« .\. D. Wek-h and L. I). Wrishl , •/. \ulritioii 25, 555 (1913). 

 20 G. A. Emerson and E. Wurtz, J'roc. Soc. Exptl. Biol. Med. 57, 47 (1944). 

 2' L. D. Wright and A. D. Welch, ./. Nutrition 27, 55 (1944). 

 " K. R. Johanson, S. K. Shapiro, and W. B. Sarles, ./. Boeteriot. 54, 35 (1947). 

 " J. R. Couch, W. W. Cravens, C. A. Elvehjem, and ,1. G. ll,di)iu, ./. Xiitrition 35, 



57 (1948). 

 2^. R. Couch, M. L. Sunde, W. W. Cravens, C. A. I';ivehieni, and ,1. G. Ilali)in, 



./. Nutrition 37, 251 (1949). 

 "^^V. W. Went and K. V. Thini.ann, IMiylolior'inoues, 'JUl pp. Macniillan Co., Xew 



York, 1937. 



