title: Repeated-batch production of glucoamylase using recombinant Saccharomyces cerevisiae immobilized in a fibrous bed bioreactor.
abstract: The recombinant Saccharomyces cerevisiae strain C468/pGAC9 has an unstable hybrid plasmid pGAC9, which directs production of glucoamylase. A fibrous cotton material with a good adsorption capability for recombinant S. cerevisiae cells was used as the immobilization matrix in an internal loop airlift-driven fibrous bed bioreactor (ILALFBB) system. With batch cultures in the ILALFBB, the fraction of plasmid-carrying cells was 72% after more than 2 days cultivation, which was two times higher than that in the conventional free-cell culture. Correspondingly, a high activity of glucoamylase (GA; 113 U/l) was achieved with a high productivity of 43 U/l/h. The ILALFBB system also maintained a high fraction of viable plasmid-carrying of 74% for glucoamylase production during repeated-batch cultures, achieving a high glucoamylase activity of 140 U/l with a productivity of 19-130 U/l/h in all 14 batches studied during 19.8 days. The stable and long-term glucoamylase production from the ILALFBB was attributed to the effect of cell immobilization on plasmid stability. Plasmid-carrying cells were preferentially retained in the fibrous matrix because of their ability to adhere to the fiber surface and to form cell aggregates higher than those of plasmid-free cells. The repeated batch using immobilized cell of recombinant S. cerevisiae in the ALALFBB system thus provides a feasible method for stable, long-term and high-level production of glucoamylase.
authors.affiliation: Department of Chemical and Biochemical Engineering, University of Western Ontario, London, ON N6A5B9, Canada.
authors.forename: Peter M
authors.initials: PM
authors.lastname: Kilonzo
authors.forename: Argyrios
authors.initials: A
authors.lastname: Margaritis
authors.forename: Maurice A
authors.initials: MA
authors.lastname: Bergougnou
mesh_terms: D019149:Bioreactors / Q000382:microbiology*; D018914:Cells, Immobilized / Q000201:enzymology*; D005087:Glucan 1,4-alpha-Glucosidase / Q000096:biosynthesis*; D003368:Gossypium; D050296:Microbial Viability; D010957:Plasmids / Q000032:analysis; D012441:Saccharomyces cerevisiae / Q000201:enzymology*; D029701:Saccharomyces cerevisiae Proteins / Q000096:biosynthesis*
chemical_list: D029701:Saccharomyces cerevisiae Proteins; D005087:Glucan 1,4-alpha-Glucosidase
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