A model system for increasing the intensity of whole-cell biocatalysis: Investigation of the rate of oxidation of D-sorbitol to L-sorbose by thin bi-layer latex coatings of non-growing Gluconobacter oxydans

Authors

  • M. Fidaleo,

    1. BioTechnology Institute, University of Minnesota, 140 Gortner Laboratories, 1479 Gortner Avenue, St. Paul, Minnesota 55108, telephone: (612) 624-9259; fax: (612) 625-1700
    2. Department of Food Science and Technology, University of Tuscia, Via S. Camillo de Lellis, Viterbo, Italy
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  • S. Charaniya,

    1. BioTechnology Institute, University of Minnesota, 140 Gortner Laboratories, 1479 Gortner Avenue, St. Paul, Minnesota 55108, telephone: (612) 624-9259; fax: (612) 625-1700
    2. Department of Chemical Engineering and Materials Science, University of Minnesota, Amundson Hall, Minneapolis, Minnesota
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  • C. Solheid,

    1. BioTechnology Institute, University of Minnesota, 140 Gortner Laboratories, 1479 Gortner Avenue, St. Paul, Minnesota 55108, telephone: (612) 624-9259; fax: (612) 625-1700
    Current affiliation:
    1. Cargill Incorporated, Biotechnology Development Center, 2500 Shadywood Road, Navarre, Minnesota 55331.
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  • U. Diel,

    1. BioTechnology Institute, University of Minnesota, 140 Gortner Laboratories, 1479 Gortner Avenue, St. Paul, Minnesota 55108, telephone: (612) 624-9259; fax: (612) 625-1700
    2. Technische Fachhochschule, Berlin, Germany
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  • M. Laudon,

    1. BioTechnology Institute, University of Minnesota, 140 Gortner Laboratories, 1479 Gortner Avenue, St. Paul, Minnesota 55108, telephone: (612) 624-9259; fax: (612) 625-1700
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  • H. Ge,

    1. Department of Chemical Engineering and Materials Science, University of Minnesota, Amundson Hall, Minneapolis, Minnesota
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  • L.E. Scriven,

    1. Department of Chemical Engineering and Materials Science, University of Minnesota, Amundson Hall, Minneapolis, Minnesota
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  • M.C. Flickinger

    Corresponding author
    1. BioTechnology Institute, University of Minnesota, 140 Gortner Laboratories, 1479 Gortner Avenue, St. Paul, Minnesota 55108, telephone: (612) 624-9259; fax: (612) 625-1700
    2. Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Gortner Laboratories, St. Paul, Minnesota
    • BioTechnology Institute, University of Minnesota, 140 Gortner Laboratories, 1479 Gortner Avenue, St. Paul, Minnesota 55108, telephone: (612) 624-9259; fax: (612) 625-1700
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  • M. Fidaleo and S. Charaniya contributed equally to portions of this work.

Abstract

We developed a novel <50-µm thick nano-porous bi-layer latex coating for preserving Gluconobacter oxydans, a strict aerobe, as a whole cell biocatalyst. G. oxydans was entrapped in an acrylate/vinyl acetate co-polymer matrix (Tg∼10°C) and cast into 12.7-mm diameter patch coatings (cellcoat) containing ∼109 CFU covered by a nano-porous topcoat. The oxidation of D-sorbitol to L-sorbose was used to investigate the coating catalytic properties. Intrinsic kinetics was studied in microbioreactors using a pH 6.0 D-sorbitol, phosphate, pyruvate (SPP) non-growth medium at 30°C, and the Michaelis–Menten constants determined. By using a diffusion cell, cellcoat and topcoat diffusivities, optimized by arresting polymer particle coalescence by glycerol and/or sucrose addition, were determined. Cryo-FESEM images revealed a two-layer structure with G. oxydans surrounded by <40-nm pores. Viable cell density, cell leakage, and oxidation kinetics in SPP medium for >150 h were investigated. Even though the coatings were optimized for permeability, ∼50% of G. oxydans viability was lost during cellcoat drying and further reduction was observed as the topcoat was added. High reaction rates per unit volume of coating (80–100 g/L · h) were observed which agreed with predictions of a diffusion-reaction model using parameters estimated by independent experiments. Cellcoat effectiveness factors of 0.22–0.49 were observed which are 20-fold greater than any previously reported for this G. oxydans oxidation. These nano-structured coatings and the possibility of improving their ability to preserve G. oxydans viability may be useful for engineering highly reactive adhesive coatings for multi-phase micro-channel and membrane bioreactors to dramatically increase the intensity of whole-cell oxidations. © 2006 Wiley Periodicals, Inc.

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