Fabrication of three-dimensional porous cellulose microsphere bioreactor for biotransformation of polydatin to resveratrol from Polygonum cuspidatum Siebold & Zucc

Abstract

In this study, in order to bio-transform polydatin to resveratrol from Polygonum cuspidatum extract, a 3D-porous structured cellulose microsphere (CMs) immobilized with β-glucosidase acted as a micro-bioreactor. To successfully immobilize β-glucosidase, CMs was treated with epoxidation to attach three different functional amion groups, and finally combined with β-glucosidase. CMs provided large surface area (32.0 m²/g) and many sites for immobilization of β-glucosidase and chemical modification. The porosity of CMs was 90 % and its density was about 1.00 g/m3. According to SEM images, the 3D-porous structure was obviously found and the result of FTIR proved the successful modification of amino groups. The crystal structure of CMs was changed from crystalline cellulose I-β to crystalline cellulose II during the sol-gel method. In the biotransformation tests of the Polygonum cuspidatum extracts, the conversion rate of polydatin reached 93.06 %, and after conversion, the concentration of resveratrol was two times higher than the original Polygonum cuspidatum extract. In addition, the cellulose microsphere micro-bioreactor also possessed good reusability, which could maintain 89.2 % activity after being repeatedly operated 8 times. Therefore, this cellulose microsphere micro-bioreactor can be successfully used to produce resveratrol from polydatin, and this micro-bioreactor may also have the potential to convert other plant glycosides into aglycones. Moreover, because of their good biocompatibility, the 3D porous cellulose microspheres can also be used for immobilization of other enzymes to prepare efficient bioreactors.