MICROBIOLOGICAL PRODUCTION 



Better yields were obtained by Moore et al}^ in shake cultures. 

 With a yeast extract-glucose-peptone broth, a concentration of 198 

 mg. per litre of liquor or 4 mg. per g. of solid was obtained in seventy- 

 two hours and with distiller's thin stillage 124 mg. per litre or 4-6 mg. 

 per g. of solids. When supplemented with molasses or corn oil, the 

 yield was increased to 356 mg. per litre. Cultures kept at low tem- 

 perature produced less riboflavine, whilst lyophilised cultures lost the 

 ability altogether. Maintenance of stock cultures on maltose broth 

 at room temperature is advocated. 



W. Ritter ^^ separated E. Ashbyii into two strains, one white and 

 one yellow, and found that the former synthesised only a fraction of 

 the riboflavine produced by the latter. The higher yields obtained 

 by the yellow variant were produced on wort agar, which gave up to 

 80 mg. per litre. Biotin was essential for growth of the organism. 



The most efficient method for the production of riboflavine by 

 fermentation with E. Ashbyii, appears to be submerged growth with 

 continuous aeration and agitation. Patents covering this process 

 were filed by Socitte des Usines chimiques Rhone-Poulenc,^^^ Com- 

 mercial Solvents Corporation,^® Pfizer & Co.,^^ Merck & Co.,^^ Lederle 

 Labs. Inc.,^^ and Roche Products Ltd.^^** In every instance, the 

 reconamended medium comprised a carbohydrate source, such as 

 glucose or molasses, together with a source of nitrogen, such as peptone, 

 animal tissue, yeast extract, corn steep liquor or skimmed milk. One 

 patent ^® advocated as an additional supplement a metabolisable 

 lipid, such as corn-, olive- or peanut-oil, or cocoa-butter ; with alcohol 

 fermentation residues and corn steep water, yields of 436 mg. per litre 

 were obtained in four days, whilst a medium containing animal tissues ^^ 

 gave up to 400 mg. per litre in a similar time, and a yeast extract- 

 molasses medium 468 mg. per litre. 



Another micro-organism that appears to be of potential value in 

 the microbiological production of riboflavine is Ashbya gossypii. 

 Small yields were obtained by Guillermond et aL^^ but considerably 

 larger amounts were obtained by Wickerham et al.,^^ who used an 

 orange-yellow variant ; with an aerated cerelose-yeast extract medium 

 at 26° to 28° C, up to 380 mg. per litre were produced after eight days. 

 The highest recorded yields of riboflavine, using Ashbya gossypii, 

 were obtained in shake cultures on a medium containing 4 % glucose, 

 0-5 % peptone and 0-5 % corn steep liquor solids ; ^^ titres of 500 to 

 600 mg. per litre were obtained, equivalent to more than 10 mg. of 

 riboflavine per g. of solid. 



Riboflavine was also obtained by fermentation with Mycobacterium 

 smegmatis, yields varying according to the speed of growth and the 

 nature of the medium. ^^ The best yields were obtained in the absence 

 of organic nitrogen. Fructose was the best source of carbon for growth 



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