318 



BIOLOGICAL ACTIVITIES OF YEASTS 



which are still going on today. He observed the ability of large 

 inocula to initiate rapid growth in media which failed to support 

 growths when small inocula were used. He concluded that bios, an 

 organic substance of biological origin essential for the propagation 

 of yeast cells, was carried over in large inocula from the previous 

 cultures. He also found that other biological materials contained 

 substances with marked stimulatory properties. 



As already indicated, considerable research has been and is being 

 done on the essential growth factors. These substances, when added 

 to a medium complete in respect to carbon and nitrogen compounds 

 and the other necessary nutrients, cause a stimulation of microbial 

 growth all out of proportion to the minute amounts added. 



The bios of Wildiers has proved to be a complex of growth-essential 

 and stimulating substances such as thiamin, biotin, pyridoxine, in- 

 ositol, and pantothenic acid. The role of the first-named compound 

 is now known. The enzyme, carboxylase, which catalyzes the de- 

 carboxylation of pyruvic acid to carbon dioxide and acetaldehyde in 

 the alcoholic fermentation, cannot function without its coenzyme, 

 cocarboxylase. Cocarboxylase is known to be diphosphothiamin. 

 The structures of the above compounds are as follows. 



O 



s 



N=C— NH2 HC C— CH2CH2OH 



i- 



CH3C C— CH2 N- 



li ji I 



N— CH CI 



-C— CH3 



HN 



HC- 



I 

 H2C 



NH 



I 

 -CH 



:H(CH2)4C00H 



Thiamin, Vitamin Bi 



H OH 



\ / 

 C 



HOCH HCOH 



HOCH HCOH 



\ / 

 C 



Biotin, Vitamin H, 

 Coenzyme R, Bios IIj 



N 



/- \ 

 HC C— CH3 



CH2OH— C 



\. 



COH 



H OH 



Inositol, Bios I 



CH2OH 

 Pyridoxine, Vitamin Be 



CH3 H O H 



CH2OH— C C— C— N— CH2CH2COOH 



I I 



CH3 OH 



Pantothenic Acid 



