产菊糖酶克鲁维酶母Y-85的明胶固定化

Immobilization of Kluyveromyces sp.Y-85 producing inulinase with gelatin matrix

克鲁维酵母Y 85的胞外菊糖酶占其总酶活的 2 8%。以 1 0 %明胶包埋该酵母 ,酶活保留率为 73.9%。与游离细胞相比 ,固定化细胞菊糖酶的最适 pH未改变 ,但当pH <4和 pH >7时酶活稳定性更高 ;最适水解温度则升高了 5℃ ,酶的热稳定性也有所提高。游离细胞的Km值为 9.3mmol/L ,固定化细胞则为 1 2 .8mmol/L。4℃贮存 30d ,固定化细胞酶活无损失。分批反应 1 0批次 ,固定化细胞酶活及机械强度保持良好 ,底物转化率在 90 %左右 ;以含 3.2 %菊糖的菊芋粉抽提液为底物进行连续反应 ,当稀释率D分别为 0 .44h-1和 2 .0h-1时 ,相应的还原糖生产力为 1 2 .5 g/l·h和 33.0g/l·h ,转化率为 92 %和 5 4%。连续反应 30d ,酶活仅损失 1 2 %。

of the total inulinase of Kluyveromyces sp. Y?85 was extracellular enzyme.When yeast cells were immobilized in 10% gelatin matrix,the retention was 73.9% of the original inulinase activity .Though optimum pH of immobilized cells for inulin hydrolysis was similar to free cells,the optimum temperature,pH stability and thermal stability of inulinase were improved by immobilization.Km values were 9.3 mM inulin for free cells and 12.8 mM inulin for immobilized cells respectively.There was no loss of enzyme activity of immobilized cells on storage at 4℃ for 30 days.After 10 batches of hydrolysis,enzyme activity and gel strength of immobilized cells remained stable,and conversion rate of substrate was about 90%.At the dilution rate of D=0.44 h -1 and 2.0 h -1 ,and the inulin extract with 32 g/L inulin concentration as substrate for continuous hydrolysis,the reducing sugar productivity were 12.5 g/l·h and 33.0 g/l·h and the corresponding conversion rates were 92% and 54% respectively.The immobilized cells just lost 12% of original inulinase activity after 30 days of continuous hydrolysis.