Biotransformation of Geniposide into Genipin by Immobilized Trichoderma reesei and Conformational Study of Genipin

Trichoderma reesei QM9414, Trichoderma viride 3.316, Aspergillus niger M85, and Aspergillus niger M92 were screened for hydrolyzing geniposide into genipin. T. reesei was selected according to the β-glucosidase activity of the fermentation broths using geniposide as a substrate. T. reesei was immobilized by embedding method using sodium alginate as the carrier. Geniposide was hydrolyzed by immobilized T. reesei at 28°C (200 rpm) for 34 h, and the yield of genipin was 89%. The product was purified and identified by UV, IR, EIMS, and (1)H-NMR. Since there were two sets of signals in (1)H-NMR spectra, a series of experiments were performed and verified that the existence of two conformations was the main reason. Generally, biotransformation of geniposide into genipin by immobilized T. reesei provides a promising solution to the genipin production.