Research Of Conversion Xylitol Production By Microorganism

Xylitol due to its excellent properties, so it has a wide range of uses in the foodindustry.It has higher price because of its complex production process. This discussionmainly focused on screening the strain for higher yield and production process of xylitolconversion, it aims to increase xylitol conversion rate and lay the foundation forindustrial production. The specific content and results are as follows:(1) At first, isolated and obtained a high yield Candida tropicalis JS-3by thin layerchromatography from collected a large number of strains.(2) Using Candida tropicalis as starting cell, mutagenized by UV and NTG. Founda higher productive strain Candida tropicalis JS-3-123-39which improved nearly23%than its parental strain.Its genetic quality was proved to be stable by experiments.(3) Culture medium, such as nitrogen source, carbon sourceand metal-salt, wereoptimized through Orthogonal experimental and Respone surface analysis. Theoptimal concentrations of the factors were obtained (g/L): xylose3.15, glucose10.25,yeast extract2, peptone3, ZnCl1.66, MgSO40.15, KH2PO44.5. The cultivationconditions of the yeast strain was studied through Orthogonal experimental and theoptimal conditions are as follows: temperature30℃, the speed was180r/min,conversion pH value5, yeast culture time was10h, a250mL flask containing100mLmedium.(4) At last, conversion onditions optimized through Single factor experiments andthe optimal conditions of the yeast cell were as followed: yeast concersion time was10h, conversion pH value5.5, temperature28℃, a250mL flask containing100mLmedium, conversion initial sugar concentration20g/L, conversion shaking speed140r/min, inoculation rate10%, The ability of conversion was as same as the native yeastcell in optimized condition. The yield of xylitol has increased to90%.