title: Impact of operating variables on the expanded bed adsorption of Saccharomyces cerevisiae cells using a concanavalin A derivatized perfluorocarbon.
abstract: The use of fluidizable affinity adsorbents for the adsorption of cells in expanded mode is investigated. Affinity adsorbents have been synthesized by immobilizing the lectin Concanavalin A onto the surface of triazine-activated perfluorocarbon-solids. The adsorbents were found to adsorb Saccharomyces cerevisiae cells from solution with adsorption capacities of up to 6.8 x 10(9) cells mL(-1). Adsorption kinetics were rapid with a time constant of </=8 min. The adsorbed cells could be eluted using 500 mM methyl alpha,D-mannopyranoside, although the kinetics of release were slowed by the multipoint nature of the interaction. The dynamic capacity of the Con A PVA FEP in expanded mode was up to 4.5 x 10(9) cells mL(-1). The operating parameters of bed height, application flow rate, and adsorbent size distribution were investigated for any potential improvements in throughput, which may improve utility for more fragile cells. A decrease in settled-bed height from 20 to 5 cm resulted in a decrease in dynamic capacity of 27% from 4.5 to 3.3 x 10(9) cells mL(-1). An increase in application flow rate from 0.7 to 2.0 mL/min(-1) (resulting in an expansion increase from two- to fourfold) resulted in a 40% decrease in dynamic capacity from 4.0 to 2.4 x 10(9) cells mL(-1). An increase in the mean size distribution of the perfluorocarbon from 42 to 69 microm and therefore the flow rate needed for twofold expansion of 0.7 to 1.5 mL/min(-1) resulted in a 56% decrease in dynamic capacity from 4.0 to 1.8 x 10(9) cells mL(-1). The expanded bed, using certain combinations of the operating parameters, therefore shows significant potential for the robust, high efficiency and high capacity capture and separation of cells.
authors.affiliation: BPL, Bio Products Laboratory, Dagger Lane, Elstree, Hertfordshire, WD6 3BX, United Kingdom.
authors.forename: R H
authors.initials: RH
authors.lastname: Clemmitt
authors.forename: H A
authors.initials: HA
authors.lastname: Chase
mesh_terms: D000327:Adsorption; D001422:Bacterial Adhesion / Q000502:physiology*; D002452:Cell Count; D002469:Cell Separation / Q000295:instrumentation / Q000379:methods*; D002846:Chromatography, Affinity / Q000295:instrumentation / Q000379:methods*; D003208:Concanavalin A / Q000031:analogs & derivatives* / Q000138:chemical synthesis / Q000493:pharmacokinetics*; D004800:Enzymes, Immobilized / Q000493:pharmacokinetics; D005466:Fluorocarbons / Q000138:chemical synthesis / Q000737:chemistry / Q000493:pharmacokinetics; D008567:Membranes, Artificial; D012441:Saccharomyces cerevisiae / Q000166:cytology / Q000302:isolation & purification* / Q000378:metabolism*
chemical_list: D004800:Enzymes, Immobilized; D005466:Fluorocarbons; D008567:Membranes, Artificial; D003208:Concanavalin A