Hsieh Hsin-Ju, Tung Kai-Yu, Nair Giridhar R, Chu I-Ming, Wu Wen-Teng
Department of Chemical Engineering, National Tsing Hua University, Hsinchu, Taiwan.
Appl Microbiol Biotechnol. 2007 Nov;77(1):53-60. doi: 10.1007/s00253-007-1148-9. Epub 2007 Sep 12.
The mycelia of Aspergillus niger, cultivated in a medium containing 45 g l(-1) maltose, 66 g l(-1) yeast extract, and 5 g l(-1) K(2)HPO(4) at 30 degrees C and 200 rpm, were used as a biocatalyst in the glucosylation of ascorbic acid. Free mycelia from 3-day-old culture, when used in a 6-h reaction with maltose as the acyl donor, gave 16.07 g l(-1) ascorbic acid glucoside corresponding to a volumetric productivity of 2.68 g l(-1) h(-1) and a conversion of 67%. Mycelia from 3-day-old cultures were entrapped in calcium alginate beads and used as a catalyst in the glucosylation of ascorbic acid. An ascorbic acid-to-maltose molar ratio of 1:9 was found to be optimum, and the conversion reached 75% after 12 h. The concentration of ascorbic acid glucoside produced at this molar ratio was 17.95 g l(-1), and the productivity was 1.5 g l(-1) h(-1). The biocatalyst was repeatedly used in a fixed bed bioreactor for the synthesis of ascorbic acid glucoside and approximately 17 g l(-1) of ascorbic acid glucoside corresponding to a volumetric productivity of 1.42 g l(-1) h(-1) was produced in each use. The conversion was retained at 70% in each use. The entrapped mycelia also exhibited exceptionally high reusability and storage stability. The product was purified to 85% by anion exchange and gel permeation chromatography with a final yield of 75%.
黑曲霉的菌丝体在含有45 g l⁻¹麦芽糖、66 g l⁻¹酵母提取物和5 g l⁻¹ K₂HPO₄的培养基中于30℃、200 rpm条件下培养，用作抗坏血酸糖基化反应的生物催化剂。3日龄培养物的游离菌丝体在以麦芽糖为酰基供体的6小时反应中使用时，产生了16.07 g l⁻¹抗坏血酸葡糖苷，体积产率为2.68 g l⁻¹ h⁻¹，转化率为67%。3日龄培养物的菌丝体被包埋在海藻酸钙珠中，并用作抗坏血酸糖基化反应的催化剂。发现抗坏血酸与麦芽糖的摩尔比为1:9时最为适宜，12小时后转化率达到75%。在此摩尔比下产生的抗坏血酸葡糖苷浓度为17.95 g l⁻¹，产率为1.5 g l⁻¹ h⁻¹。该生物催化剂在固定床生物反应器中反复用于合成抗坏血酸葡糖苷，每次使用时产生约17 g l⁻¹抗坏血酸葡糖苷，体积产率为1.42 g l⁻¹ h⁻¹。每次使用时转化率保持在70%。包埋的菌丝体还表现出极高的可重复使用性和储存稳定性。通过阴离子交换和凝胶渗透色谱法将产物纯化至85%，最终产率为75%。
