XIII. REQUIREMENTS 615 



intestinal circulation, respiration, or secretion of gastric acid. A single oral 

 dose of biotin to the biotin-deficient rat has no influence on metabolic rate 

 or renal function. Repeated oral doses appear to lower the metabolic rate 

 A slight delay in the healing time of injured skin areas was apparent after 

 local or oral application of biotin to biotin-deficient rats. 



XIII. Requirements 



PAUL GYORGY 



Biotin is one of the most powerful catalysts of several metabolic reactions, 

 needed onlj^ in minute amounts. As such it is apparently required by 

 animals, plants, and by a large number of bacteria. In animals living in 

 symbiosis with some biotin-producing bacteria, it becomes difficult to assess 

 the exogenous requirements. 



In bacteria, the synthesis of aspartic acid and that of oleic acid is in- 

 timately linked with the presence of biotin. Several other metabolites, the 

 production of which may be catalyzed by biotin, are either apparently 

 dispensable or else can be obtained through alternate pathways. 



A. YEASTS AND OTHER FUNGI 



Biotin is essential for the growth of many strains of Saccharomyces 

 cerevisiae^ ■ - and for the majority of a large number of other yeasts tested.'-^ 

 Some of the analogs of biotin, such as desthiobiotin (see p. 562), may 

 replace biotin for many yeasts but not for bacteria.^ Biotin definitely in- 

 creases the production of alcohol by yeast.^ The uptake of biotin is corre- 

 lated with the requirement in different species of yeasts. Some strains of 

 yeasts, such as Torulopsis uiilis and Hansenula anomala, are able to syn- 

 thesize biotin and do not utilize the biotin of the medium.'-' 



Biotin was found to be essential for a number of molds, including Lophio- 

 dermum pinasiri and Ashbya (Nematospora) gossypii,^^ Trichophyton album 



1 R. J. Williams, R. E. Eakin, and E. E. Snell, /. Am. Chem. Soc. 62, 1204 (1940). 



2 L. H. Leonian and V. G. Lill)^ Am. J. Botany 29, 459 (1942). 



3 P. R. Burkholder, Am. J. Botany 30, 206 (1943). 



* P. R. Burkholder and D. Moyer, Bull. Torrey Botan. Club 70, 372 (1943). 

 « P. R. Burkholder, I. McVeigh, and D. Moyer, /. Bacterial. 48, 385 (1944). 

 « A. S. Schultz and L. Atkin, Arch. Biochem. 14, 369 (1947). 



» J. L. Stokes and M. Gunness, J. Biol. Chem. 157, 121 (1945). 



* V. de Souza and M. Sreenivasaya, J . Sci. Med. Research (India) 4, 384 (1945). 

 » Wei-Shen Chang and W. H. Peterson, ./. Bacteriol. 58, 33 (1949). 



>" F. Kogl and N. Fries, Hoppe-Seyler's Z. phi/siol. Chem. 249, 93 (1937). 



