Study Of Nutritional Yeast Of Rich Riboflavin

In the paper,determination of yeast intraceller riboflavin,selection of parent strain, breeding of yeast pruducing rich intraceller riboflavin as well as optimization of mediun and fermention conditions were studied.By comparison, it was shown that fluoroscopic method is the most suitable method in determinating intraceller riboflavin because of its good recurrence, veracity, linearity between response and content of riboflavin and is little affected by solution system and high- pressure steaming is a valid method of distilling intraceller riboflavin.Indices of six strains of yeast including the riboflavin yield, nucleic acid and raw protein, autolytic ratio and biomass, were determined and compared. RY-3 with moderate growth ratio , biomass,nucleic acid and raw protein is choosen for parent strain because of its higher autolytic ratio and riboflavin yield.The factors with important influence on yeast intraceller riboflavin yield were dicided as biotin,K2HPO4and dissolved oxygen throuth P-B selecting-fator experiment. The optimal concentrations of metal ions in the medium were desided as MgSO4. 7H20 1. 1 g/L, CoSO-i. 7H? 28 mg/L, CuS(k 5H20 0. 01 mg/L, MnCl2O. 02 mg/L, ZnSOt. 7H20 34 mg/L, FeSO4. 7H20 14 mg/L throuth uniform design.The optimization of fermention conditions suggest that oxygen concertration has distint effect on riboflavin yield and higher oxygen concertration, lower preliminary pH and lesser inoculation is benefitful to riboflavin yield.A strain with growth ratio and riboflavin yield have been greatly increased is obtained throuth mutation,its riboflavin yield has increased by 79.97%,can reach 86.38 mg/kg.