Highly efficient bioconversion of flavonoid glycosides from citrus-processing wastes in solvent-buffer systems
Highly efficient bioconversion of flavonoid glycosides from citrus-processing wastes in solvent-buffer systems
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在溶剂缓冲系统中高效生物转化柑橘加工废物中的黄酮苷
DOI：
10.1039/d0gc00669f
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发表时间：
2020
期刊：
影响因子：
9.8
通讯作者：
Guanglei Zhao
中科院分区：
文献类型：
--
作者：
Yucong Zou;Xuan Xin;Haixia Xu;Hongwei Yuan;Xiaofeng Li;Yigang Yu;Guanglei Zhao
开发了一种高效的全细胞生物催化方法，用于级联水解黄酮苷以获得具有高底物转化率的有价值的水解产物。尼日尔曲霉细胞同时具有α-L-鼠李糖苷酶和β-D-葡萄糖苷酶活性，可一锅法催化橙皮苷（HES）水解：（1）α-L-鼠李糖苷酶催化HES水解为橙皮素-7-O-葡萄糖苷（HG），随后β-D-葡萄糖苷酶催化HG水解为橙皮素;（2）β-D-葡萄糖苷酶催化HES直接水解为橙皮素。通过调节关键反应条件和添加不同的糖，可以控制羟乙基淀粉的转化率和产物组成。值得注意的是，通过使用绿色溶剂代替用于溶解极性底物的传统有机溶剂，实现了HES的高转化率（高于90%）。缓冲溶液中天然低共熔溶剂（NADES）的种类和浓度明显影响电池的催化活性和选择性。倒置荧光显微镜和OD 260/OD 280分析表明，NADES可以增强细胞膜的通透性，但高浓度的NADES可能会损伤细胞膜并降低酶的活性。此外，全细胞催化剂显示出良好的放大能力和稳定性。全细胞对各种柑橘类黄酮苷及其衍生物也显示出相对较宽的底物谱，底物转化率为58.1%-98.2%，单糖苷百分比为73.3%-98.9%。这种用于黄酮苷的一锅级联水解的全细胞催化的展示为从廉价物质生产有用且有价值的黄酮单糖苷和糖苷配基提供了生态友好的、可扩展的和灵活的平台方法。
An efficient whole-cell biocatalytic method was developed for the cascade hydrolysis of flavonoid glycosides to their valuable hydrolyzates with high substrate conversions. Cells of Aspergillus niger showed both α-L-rhamnosidase and β-D-glucosidase activities, catalyzing the hydrolysis of hesperidin (HES) through two pathways in one pot: (1) α-L-rhamnosidase catalyzed HES hydrolysis to hesperetin-7-O-glucoside (HG) and subsequently β-D-glucosidase catalyzed HG hydrolysis to hesperetin, and (2) β-D-glucosidase catalyzed direct hydrolysis of HES to hesperetin. Both the HES conversion and product composition were controllable by adjusting the key reaction conditions and addition of different sugars. Remarkably, high conversions (above 90%) of HES were achieved by using green solvents in place of traditional organic solvents for dissolving polar substrates. The type and concentration of natural deep eutectic solvents (NADESs) in buffer solutions evidently influenced both the catalytic activity and selectivity of the cells. Inverted fluorescence microscopy and OD260/OD280 analysis suggested that NADESs can enhance the cellular membrane permeability, but high concentration of NADESs may damage cellular membranes and reduce the activity of enzymes. Furthermore, the whole-cell catalysts showed good scaled-up capability and stability. The whole cells also showed a relatively broad substrate spectrum towards various citrus flavonoid glycosides and their derivatives, with substrate conversions of 58.1%–98.2% and monoglycoside percentages of 73.3%–98.9%. This demonstration of whole-cell catalysis for one-pot cascade hydrolysis of flavonoid glycosides offers an eco-friendly, scalable and flexible platform method for the production of useful and valuable flavonoid monoglycosides and aglycones from inexpensive substances.