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Indexed by:期刊论文

Date of Publication:2010-11-15

Journal:BIOCHEMICAL ENGINEERING JOURNAL

Included Journals:SCIE、EI、Scopus

Volume:52

Issue:2-3

Page Number:123-130

ISSN No.:1369-703X

Key Words:Dioscorea zingiberensis; Aspergillus oryzae; Diosgenin; Biotransformation; Pathways analysis; Kinetic modeling

Abstract:In this paper the pathways and kinetics for the production of diosgenin via biotransformation of Dioscorea zingiberensis C H Wright by Aspergillus oryzae ClCC 2436 were analyzed After 120 h of biotransformation at 30 C the concentration of diosgenin in the culture reached 36 87 +/- 1 27 mu mol/g raw herb which was 21 2 times its initial concentration A number of steroidal compounds were also isolated as minor products from the biotransformation and one of these was identified as a novel compound named 3-O-beta-D-glucopyranosyl (1 -> 3) - beta-D-glucopyranosyl (1 -> 4) - beta-D-glucopyranosyl-diosgenin (diosgenin-triglucoside) The biotransformation consisted of two stages the release of steroids from the herb (accompanied by fungal growth) and hydrolysis of the steroids by glycosidases Kinetic analysis and mathematical modelling showed that the process of biotransformation could be described by first-order kinetics under the condition of high K-m[S] values It consisted of a cascade of consecutive and parallel reactions involving three kinds of enzymes five steroid saponins and their sapogenin The main hydrolysis reactions that led to the production of diosgenin were also discussed (C) 2010 Elsevier B V All rights reserved