title: 11 alpha-Hydroxylation of progesterone in biphasic media using alginate-entrapped Aspergillus ochraceus gel beads coated with polyurea.
abstract: A novel cell-immobilization technique was developed in this study for increasing substrate partition to the gel matrix by coating a polyurea thin layer on the surface of Ca-alginate beads. The proposed method was simple and could be performed under mild conditions. The bioconversion of progesterone to 11 alpha-hydroxyprogesterone with these polyurea-coating alginate-entrapped Aspergillus ochraceus cells was investigated using different organic solvents in biphasic media. The reaction medium of ethyl acetate could markedly enhance the bioconversion rate with the existence of a hydrophobic layer, most likely resulting from the increasing partition of substrate to gel matrix. Bioconversion with higher substrate concentration was possible using an ethyl acetate-water medium. The conversion rate increased almost linearly with increasing substrate concentration from 10 to 80 g l-1. The rate with 80 g l-1 progesterone increased up to six times greater than the rate with the immobilized cells without coating, and also exhibited a much higher rate than that reported in the literature.
authors.affiliation: Department of Chemical Engineering, National Tsing Hua University, Hsinchu, Taiwan, Republic of China.
authors.forename: J Y
authors.initials: JY
authors.lastname: Houng
authors.forename: W P
authors.initials: WP
authors.lastname: Chiang
authors.forename: K C
authors.initials: KC
authors.lastname: Chen
authors.forename: C
authors.initials: C
authors.lastname: Tiu
mesh_terms: D000464:Alginates; D001230:Aspergillus / Q000378:metabolism*; D001709:Biotechnology / Q000379:methods; D020723:Glucuronic Acid; D006603:Hexuronic Acids; D006900:Hydroxylation; D006908:Hydroxyprogesterones; D007700:Kinetics; D008855:Microscopy, Electron, Scanning; D011108:Polymers; D011374:Progesterone / Q000378:metabolism*
chemical_list: D000464:Alginates; D006603:Hexuronic Acids; D006908:Hydroxyprogesterones; D011108:Polymers; C030228:11-hydroxyprogesterone; C045786:polyurea; D011374:Progesterone; D020723:Glucuronic Acid