title: Optimization of ginsenosides hydrolyzing beta-glucosidase production from Aspergillus niger using response surface methodology.
abstract: To optimize ginsenosides hydrolyzing beta-glucosidase production from Aspergillus niger, response surface methodology was carried out in two stages. The Plackett-Burman design was achieved to screen the important variables that influence beta-glucosidase production. Among 10 variables (wheat bran, soybean powder, CaCl(2), ginsenosides, KH(2)PO(4), MgSO(4), polyethylene glycol (PEG), medium volume, inoculum size, and stirring speed), it was found that wheat bran, KH(2)PO(4), and stirring speed had significant effect on beta-glucosidase activity due to very low p-values (p<0.05). Subsequently, wheat bran, KH(2)PO(4), and stirring speed were further optimized using central composite design. The optimal beta-glucosidase production was predicted to be 4650.14 U/ml with the combination of factors (wheat bran, 34.51 g/l; KH(2)PO(4), 1.78 g/l; stirring speed, 161.60 rpm/min). Finally, under optimal fermentation conditions, ginsenoside Rb(1) was converted to Rd and F(2) by A. niger within 10 min. Little compound K was detected at 30 min, and finally F(2) was completely transformed to compound K within 8 h. The putative conversion pathway of Rb(1) by A. niger was Rb(1), Rd, F(2), and compound K.
authors.affiliation: Department of Food Science and Technology, College of Agriculture and Biotechnology, Chungnam National University, Daejon 305-764, Republic of Korea.
authors.forename: Jiang-Ning
authors.initials: JN
authors.lastname: Hu
authors.forename: Xue-Mei
authors.initials: XM
authors.lastname: Zhu
authors.forename: Ki-Teak
authors.initials: KT
authors.lastname: Lee
authors.forename: Yi-Nan
authors.initials: YN
authors.lastname: Zheng
authors.forename: Wei
authors.initials: W
authors.lastname: Li
authors.forename: Li-Kun
authors.initials: LK
authors.lastname: Han
authors.forename: Zhe-Ming
authors.initials: ZM
authors.lastname: Fang
authors.forename: Li-Juan
authors.initials: LJ
authors.lastname: Gu
authors.forename: Bai-Sheng
authors.initials: BS
authors.lastname: Sun
authors.forename: Chun-Yan
authors.initials: CY
authors.lastname: Wang
authors.forename: Chang-Keun
authors.initials: CK
authors.lastname: Sung
mesh_terms: D001234:Aspergillus niger / Q000187:drug effects* / Q000201:enzymology*; D002851:Chromatography, High Pressure Liquid; D003470:Culture Media; D003627:Data Interpretation, Statistical; D004353:Drug Evaluation, Preclinical; D036145:Ginsenosides / Q000378:metabolism*; D013056:Spectrophotometry, Ultraviolet; D013268:Stimulation, Chemical; D014908:Triticum / Q000737:chemistry; D001617:beta-Glucosidase / Q000096:biosynthesis*
chemical_list: D003470:Culture Media; D036145:Ginsenosides; C442759:ginsenoside Rb1; D001617:beta-Glucosidase