RIBOFLAVINE 



20. M. Tishler, J. W. Wellman and K. Ladenburg, /. Amer. Chem. 



Soc, 1945, 67, 2165. 



21. M. Tishler, K. Pfister, R. D. Babson, K. Ladenburg and A. J. 



Fleming, ibid., 1947, 69, 1487. 



22. F. Bergel, A. Cohen and J. W. Haworth, /. Chem. Soc, 1945, 165 ; 



B.P. 550169 ; 550836. 



5. MICROBIOLOGICAL PRODUCTION OF RIBOFLAVINE 



It is unusual for a synthetic method of producing a commercially 

 important chemical to be displaced by a method based on its isolation 

 from natural sources ; generally, the tendency is in the reverse direc- 

 tion. Yet the production of riboflavine can now be effected more 

 cheaply by fermentation than by chemical synthesis. 



Patents were filed as early as 1937 for the production of " vitamin 

 B2 " concentrates by fermenting whey or other milk by-products 

 with lactose-fermenting yeasts, especially Saccharomyces fragilis, or 

 with Clostridium butylicum, several species of Lactobacilli or with 

 moulds, 1 or by fermenting molasses or other carbohydrate mashes 

 with various strains of butanol-producing Clostridia,^ especially CI. 

 acetobiitylicum. The vitamin was recovered from the fermented 

 liquors by adsorption and elution. This process often gave low yields, 

 which were subsequently shown ^ to be due to the presence of certain 

 metals, particularly iron. The use of a mash prepared from cereals 

 containing only traces of these metals was said to give much higher 

 yields — up to 2 mg. of riboflavine per gram of dry matter. Fermenta- 

 tion of brown rice was also said to give good yields, especially in 

 admixture with maize.* 



Fermentation with Clostridia 



The first report in the scientific literature that a fluorescent pigment 

 resembling riboflavine was produced by CI. acetobutylicum was m.ade 

 by I. Yamasaki and W. Yositome.^ They used a sterilised starchy 

 medium prepared from cereals, and stated that the addition of calcium 

 carbonate was necessary for the formation of optimal amounts. The 

 riboflavine was recovered by adsorption on fuller's earth, elution of 

 the adsorbate with aqueous pyridine-methanol and precipitation with 

 acetone. The process was protected by a patent filed in 1938.^ The 

 pigment was subsequent!}^ identified as riboflavine,"^ and a detailed 

 investigation was made ^ of the effect on the yield of varying the 

 composition of the medium. It was found that iron had a markedly 

 toxic effect, 36 to 70 p. p.m. suppressing riboflavine production entirely. 

 The deleterious effect of iron was confirmed by other workers.^ The 



148 



