优化了黑曲霉 A．niger 6640 发酵制备蔗果低聚糖的发酵条件，研究了 A．niger 6640 中 β-呋喃果糖苷转移酶(β-Ffase)的性质，用阴离子柱 DEAE Sepharose CL-6B 对 β-Ffase 进行了分离纯化，用 SDS-PAGE 电泳初步分析了 β-Ffase 的分子质量． 结果表明:A.niger 6640 发酵制备 FOS 的最佳 pH 值为 7. 6、最佳发酵时间为 40 h、最佳发酵温度为33℃、最佳蔗糖质量分数为 40%;在磷酸氢二钠 － 柠檬酸缓冲液中，采用真空干燥工艺从A．niger 6640 中制得的 β-Ffase 的催化反应的最佳 pH 值为6. 5、最佳反应时间为16h、最适酶用量为 0. 19g;分离纯化得到的 β-Ffase 的分子质量约为 75ku．

In this paper，the preparation conditions of fructooligosaccharides (FOS) via the biotransformation by Aspergillus niger 6640 (A．niger 6640) were optimized，and the properties of crude enzyme of β-Ffase from A． ni-ger 6640 were investigated． Then，β-Ffase was isolated and purified by using an anion column of DEAE Sepharose CL-6B，and its molecular mass was preliminarily measured by means of SDS-PAGE electrophoresis． The results show that (1) the optimal conditions for FOS preparation should be controlled at a pH value of 7． 6，a fermentation time of 40 h，a fermentation temperature of 33 ℃ and a sucrose mass fraction of 40%; (2) in the buffer of Na 2 HPO 4 -citric acid for the biotransformation using vacuum-dried β-Ffase，the optimal conditions are determined as pH 6． 5，a reaction time of 16h and a β-Ffase dosage of 0． 19g; and (3) the molecular mass of β-Ffase after isola-tion and purification is about 75ku．