title: Production of dextransucrase by Leuconostoc mesenteroides immobilized in calcium-alginate beads: I. Batch and fed-batch fermentations.
abstract: In batch fermentation Leuconostoc mesenteroides immobilized in calcium alginate beads produced a total dextransucrase activity equal to about 93% of that by free, suspended bacterial cells under comparable conditions in a bubble column reactor. Continuous sucrose feeding (5 g/L h) to the immobilized-cell culture in the airlift bioreactor increased production of enzymatic activity by about 107% compared with ordinary batch operation of this reactor. About 14% of the enzymatic activity produced by the immobilized cells appears as soluble activity in the cell-free broth compared with about 40% in case of free cells. In an airlift bioreactor, both the soluble and the intact (sorbed and entrapped) enzymatic activity produced by the immobilized bacterial cells was about 34% greater under automatic pH control, compared to that produced in a bubble column reactor with only manual pH control. During formation of dextran by intact enzyme within cells and beads, declines are observed in apparent enzymatic activity.
authors.affiliation: Department of Chemical Engineering and Biotechnology Center, University of Connecticut, Storrs, Connecticut 06268, USA.
authors.forename: A H
authors.initials: AH
authors.lastname: El-Sayed
authors.forename: W M
authors.initials: WM
authors.lastname: Mahmoud
authors.forename: R W
authors.initials: RW
authors.lastname: Coughlin