title: Continuous production of n-butanol by Clostridium pasteurianum DSM 525 using suspended and surface-immobilized cells.
abstract: For n-butanol production by Clostridium pasteurianum DSM 525, a modified reinforced Clostridium medium was used, where glucose was alternated with glycerol and two kinds of continuous fermentation were tested using suspended and surface immobilized cells on corn stover pieces. A steady state, with butanol productivity of 4.2g/Lh, was reached during the packed-bed continuous fermentation at a dilution rate of 0.44h(-1). The average n-butanol concentration, yield and the ratio of n-butanol/liquid by-products were 10.4g/L, 33 % and 2.5, respectively. Unexpectedly, during continuous fermentation with suspended cells, at a dilution rate of 0.01h(-1), steady-state was not achieved and regular oscillations occurred in all measured variables, i.e. concentrations of glycerol, products and the number of cells stained with the fluorescent dyes carboxy fluorescein diacetate and propidium iodide. A possible explanation for oscillatory/steady-state behavior of suspended/surface-attached cells, respectively, may be specific butanol toxicity (toxicity per cell), which was higher/lower in respective cases, and which might be caused by lower/higher cell numbers respectively in both systems.
authors.affiliation: Department of Biotechnology, University of Chemistry and Technology, Prague, Czech Republic; Department of Biotechnology and Life Sciences, University of Insubria, Varese, Italy; "The Protein Factory" Research Center, Politecnico of Milano, ICRM CNR Milano and University of Insubria, Varese, Italy.
authors.forename: Alessandro
authors.initials: A
authors.lastname: Gallazzi
authors.affiliation: Department of Biotechnology, University of Chemistry and Technology, Prague, Czech Republic.
authors.forename: Barbora
authors.initials: B
authors.lastname: Branska
authors.affiliation: Department of Biotechnology and Life Sciences, University of Insubria, Varese, Italy; "The Protein Factory" Research Center, Politecnico of Milano, ICRM CNR Milano and University of Insubria, Varese, Italy.
authors.forename: Flavia
authors.initials: F
authors.lastname: Marinelli
authors.affiliation: Department of Biotechnology, University of Chemistry and Technology, Prague, Czech Republic. Electronic address: petra.patakova@vscht.cz.
authors.forename: Petra
authors.initials: P
authors.lastname: Patakova
mesh_terms: D020001:1-Butanol / Q000378:metabolism*; D061249:Batch Cell Culture Techniques; D019149:Bioreactors; D001709:Biotechnology / Q000379:methods*; D018914:Cells, Immobilized / Q000166:cytology* / Q000378:metabolism* / Q000648:ultrastructure; D003013:Clostridium / Q000166:cytology / Q000378:metabolism* / Q000648:ultrastructure; D005285:Fermentation; D014866:Waste Products / Q000032:analysis; D003313:Zea mays / Q000737:chemistry
chemical_list: D014866:Waste Products; D020001:1-Butanol
keywords: Clostridium pasteurianum; Flow cytometry; Glycerol fermentation; n-Butanol