title: Microencapsulation of recombinant Saccharomyces cerevisiae cells with invertase activity in liquid-core alginate capsules.
abstract: As a means of integrating cell growth and immobilization, recombinant Saccharomyces cerevisiae cells with invertase activity were immobilized in liquid-core alginate capsules and cultured to a high density. S. cerevisiae cells of SEY 2102 (MAT alpha ura3-52 leu2-3, 112 his4-519) harboring plasmid pRB58 with the SUC2 gene coding for invertase were grown to 83 g/L of liquid-core volume inside the capsule on a dry weight basis. The cloned invertase was expressed well in the immobilized cells with slightly higher activity than the free cells in a batch culture. Invertase in the immobilized cells showed slightly more improved thermal stability than in the free cells. Storage in a Na-acetate buffer at 4 degrees C and 10 degrees C for 1 month resulted in 7% and 8% loss in activity, respectively. The sucrose hydrolysis reaction was stably maintained for 25 repeated batches for 7 days at 30 degrees C. Continuous hydrolysis of 0.3 M sucrose was carried out in a packed bed reactor with a conversion of more than 90% at a maximum productivity of 55.5 g glucose/L per hour for 7 days. In a continuous stirred tank reactor, the maximum productivity of 80.8 g glucose/L per hour was achieved at a conversion of 59.1% using 1.0 M sucrose solution, and 0.5 M sucrose solution was hydrolyzed for 1 week with a 95% conversion at a productivity of 48.8 g/L per hour.
authors.affiliation: Department of Chemical Engineering and Bioprocess Engineering Research Center, Korea Advanced Institute of Science and Technology, Daeduk Science Town, Taejon 305-701, Korea.
authors.forename: H N
authors.initials: HN
authors.lastname: Chang
authors.forename: G H
authors.initials: GH
authors.lastname: Seong
authors.forename: I K
authors.initials: IK
authors.lastname: Yoo
authors.forename: J K
authors.initials: JK
authors.lastname: Park
authors.forename: J H
authors.initials: JH
authors.lastname: Seo