title: Production of gluconic acid by Aspergillus niger immobilized on polyurethane foam.
abstract: Production of gluconic acid by cells of Aspergillus niger immobilized on polyurethane foam was studied in repeated-batch shake-flask and bubble-column fermentations. For passive immobilization, various amounts of polyurethane foam and spore suspension were tested in order to obtain a suitable combination for optimal concentration of immobilized biomass. Immobilized cells were successfully reused with higher levels of product formation being maintained for longer period (65-70 h) than free cells. The highest gluconic acid concentration of about 143 g l-1 was reached on hydrol-based production medium with 0.3-cm3 foam cubes in the bubble column, where the effect of more suitable aeration and particle volume: medium volume ratio scheme was also investigated.
authors.affiliation: Institute of Microbiology, Bulgarian Academy of Sciences, Sofia.
authors.forename: N B
authors.initials: NB
authors.lastname: Vassilev
authors.forename: M C
authors.initials: MC
authors.lastname: Vassileva
authors.forename: D I
authors.initials: DI
authors.lastname: Spassova
mesh_terms: D001234:Aspergillus niger / Q000378:metabolism* / Q000648:ultrastructure; D001709:Biotechnology; D005069:Evaluation Studies as Topic; D005285:Fermentation; D005942:Gluconates / Q000378:metabolism*; D008855:Microscopy, Electron, Scanning; D011140:Polyurethanes; D013499:Surface Properties
chemical_list: D005942:Gluconates; D011140:Polyurethanes; C028279:polyurethane foam; C030691:gluconic acid