该研究采用微生物转化法，以橙皮苷为底物，利用黑曲霉菌株（Aspergillus niger CP-2）进行定向生物转化制备橙皮素，通过对黑曲霉菌种接种量、pH值、底物浓度、反应温度以及恒温摇床转速进行单因素实验，并选择接种量、pH值、底物浓度三个重要影响因素进行正交实验，以探究出最适转化条件。结果表明：通过高效液相色谱法（HPLC）对Aspergillus niger CP-2生物转化的产物鉴定，确定为橙皮素，最终确定的最佳工艺为：黑曲霉接种量为10%、pH值为7.5、橙皮苷底物浓度为1.0 mmol/L、反应温度为37 ℃、恒温摇床转速为200 r/min。在此反应体系下反应24 h后，得到的橙皮素产率为63.90%；此外，转化产物橙皮素的抗氧化活性以及对H2O2损伤HCK-8细胞的保护能力均高于转化底物橙皮苷，因此，黑曲霉的生物转化技术可为柑橘属副产物活性物质的高值化利用提供理论依据。

In this study, microbial transformation method was used to prepare hesperetin by directed biotransformation using Aspergillus nigerstrain (A. niger CP-2) with hesperidin as the substrate. Single factor experiments were carried out on the inoculation amount of A. niger strain, pH, substrate concentration, reaction temperature, and speed of the constanttemperature shaker, then the three important influencing factors, inoculation amount, pH, and substrate concentration were selected for the Orthogonal experiments to investigate the optimal transformation conditions. The results showed that the product of A. niger CP-2 biotransformation was identified as hesperetin by high performance liquid chromatography (HPLC), and the optimal process was determined as follows: inoculum amount of A. niger was 10%, pH value was 7.5, the concentration of hesperidin substrate was 1.0 mmol/L, the temperature of the reaction was 37 ℃, and the speed of the shaking machine was 200 r/min. After 24 h of reaction in this reaction system, the yield of hesperetin was 63.90%. Moreover, the antioxidant activity of the transformed product, hesperetin, and its protective ability against H2O2-induced damage to HCK-8 cells were higher than those of the transformation substrate, hesperidin. Therefore, the biotransformation technology using A. niger can provide a theoretical basis for the high-value utilisation of the active substances in the citrus by-products of the genus Citrus.

岭南现代农业科学与技术广东省实验室河源分中心自主科研项目（DT20220028）；广州市科技计划项目（2023B03J1370）；国家重点研发计划项目（2021YFD1600104）；广东省现代农业产业技术体系创新团队建设项目（2023KJ110）；广东省农业科学院项目（R2020PYJX011；202109TD）