Sodium alginate-grafted beta-cyclodextrins as a matrix for immobilized Arthrobacter simplex for cortisone acetate biotransfromation

Cyclodextrins (CDs) are used to resolve the low aqueous solubility of steroids, but the high cost of CDs is still a limiting factor in biotransformation process. This study, which is based on grafting and immobilization techniques, focused on synthesizing for the first time sodium alginate (SA)-grafted beta-CD (SA-beta-CD) and alginate-grafted beta-CD for the immobilization of Arthrobacter simplex (ASP) cells (SA-beta-CD-cells) and subsequent recycling of CDs and cells. FTIR spectium and X-ray diffraction proved that beta-CD was successfully grafted with SA, whereas the grafting yield of beta-CD was 10.3 mu mol g (1). SA-beta-CD could increase the solubility of CA by 3.5-fold, whereas the transformation rate was enhanced by 10%. The conversion ratio of CA was over 92% after the SA-beta-CD recycling for nine cycles. In addition, after SA-beta-CD-cells were applied in biocatalytic reactions for eight cycles, the conversion ratio of CA was over 90%. These advantages suggest great potential for using both grafting and immobilized techniques in steroid transformation. (C) 2018 Elsevier B.V. All rights reserved.