Abstract: Using corn starch as raw material,the porous starch was prepared by enzymatic hydrolysis. Polyethyleneimine as surface modifier and glutaraldehyde as crosslinking agent were used to modify the surface of porous starch,and the preparation conditions were optimized based on their sedimentation volumes. The charge distribution on the surface of modified porous starch was analyzed by Zeta potential meter,and its external morphology was observed by scanning electron microscope. The results showed that the ideal porous starch was obtained by operating under the conditions as the mixing ratio of α-amylase to glucoamylase,1∶4;the amount of mixture enzyme,5%;the pH of the reaction system,about 6; the enzymatic reaction temperature,45℃ and reaction time,24h. The optimum conditions for the surface modification of porous starch were that the reaction system contained 6% polyethyleneimine,5% glutaraldehyde,and stirred at 35℃ for 8h. The porous starch prepared under those conditions yielded the best shape and more surface charge distribution,and its isoelectric point reached 9.8. The starch immobilized E coli was preparedwhen E. coli were immobilized using the porous starch with the surface modification as the carrier under the acidic condition.

Key words: porous starch, immobilized microorganism, Zeta potential, surface modification, carrier

摘要： 以玉米淀粉为原材料，利用生物酶解法制备多孔淀粉，并以聚乙烯亚胺（PEI）为表面改性剂，以戊二醇（GA）为交联剂，对多孔淀粉进行交联改性。以沉降积为指标，优化确定多孔淀粉改性的最佳工艺条件。利用Zeta电位仪检测分析改性多孔淀粉颗粒表面的电荷分布情况，并通过扫描电子显微镜观察改性多孔淀粉的外部形貌。α-淀粉酶和糖化酶的混合比例为1∶4，酶添加量为5%，反应体系pH保持6左右，在45℃条件下酶催化反应24h时，可制备出外部形态完整、表面分布较多孔洞的多孔淀粉。以GA为交联剂，用PEI对多孔淀粉表面进行改性的最佳条件为：PEI添加量6%，GA添加量5%，35℃条件下搅拌反应8h。此条件下制备的改性多孔淀粉，形态保持完整，沉降积表现最佳，且颗粒表面分布丰富的正电荷，等电点达到9.8。以表面改性的多孔淀粉为载体，在酸性条件下固定化大肠杆菌，制备了淀粉固定化大肠杆菌。

关键词: 多孔淀粉, 固定化微生物, Zeta电位, 表面改性, 载体