Growth and production of cholesterol oxidase by alginate-immobilized cells of Rhodococcus equi No. 23.
Rhodococcus equi No. 23 was immobilized in calcium alginate. No detrimental effect on the viability of the test organism was observed during the immobilization procedure. Approx. 98% of the cell population originally present in the alginate solution were immobilized in the gel beads. When the cells of an equal volume of the culture, obtained respectively at exponential phase (12 h preculture), late-exponential phase (20 h preculture) or stationary phase (36 h preculture) were immobilized, the gel beads prepared with the stationary-phase culture were found to contain the highest cell population [about 10(8) colony-forming units (CFU)/g of beads]. In addition, gel beads, prepared with late-exponential-phase culture, exhibited the highest production of cholesterol oxidase (CholOx) after 48 h of incubation. Increasing the bead mass from 3.5 to 14.0 g/100 ml of medium increased CholOx production. However, further increasing the bead mass resulted in a reduction of CholOx production. Furthermore, on the basis of a similar initial cell population, the alginate-immobilized cells of R. equi No. 23 produced a significantly higher amount of CholOx (P<0.05) than did the free cells.
Chang
Yu-Chih
YC
Graduate Institute of Food Science and Technology, National Taiwan University, Taipei, Taiwan.
Chou
Cheng-Chun
CC
D000464:Alginates / Q000648:ultrastructure; D018914:Cells, Immobilized / Q000201:enzymology; D002789:Cholesterol Oxidase / Q000096:biosynthesis*; D020723:Glucuronic Acid; D006603:Hexuronic Acids; D016929:Rhodococcus equi / Q000201:enzymology* / Q000648:ultrastructure
D000464:Alginates; D006603:Hexuronic Acids; D020723:Glucuronic Acid; D002789:Cholesterol Oxidase