Riboflavin Biosynthesis by Candida robusta

During the study on the oxidative sugar metabolism of yeasts, it was found that six strains of Candida robusta, isolated from fruits, produced large amounts of yellow pigment in shaking culture and this pigment was identified as riboflavin. Riboflavin production by C. robusta has never been reported.

Some notable characteristics of C. robusta in riboflavin production were found. As nitrogen sources, ammonium salts and urea were favorable, but nitrate and organic nitrogen sources such as glycine, asparagine and peptone were not utilized for riboflavin production. Riboflavin was not produced in still culture; a highly aerobic condition, as may be obtained by shaking culture, wa, essential. The addition of excess CaCO₃ was also necessary. Acetic acid, added as the Ca salt in its production as a sole carbon source, was more effective than sugars and optimum concentration of this acid was 7%. Riboflavin were obtained in yields as high as 32 to 34 mg % from the acetate medium after 8 days.