Monitoring of complex industrial bioprocesses for metabolite concentrations using modern spectroscopies and machine learning: Application to gibberellic acid production

Authors

  • Aoife C. McGovern,

    1. Institute of Biological Sciences, Cledwyn Building, University of Wales, Aberystwyth, Ceredigion SY23 3DD, Wales, UK; telephone: +44-(0)-1970-621-947; fax: +44-(0)-1970-622-354
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  • David Broadhurst,

    1. Institute of Biological Sciences, Cledwyn Building, University of Wales, Aberystwyth, Ceredigion SY23 3DD, Wales, UK; telephone: +44-(0)-1970-621-947; fax: +44-(0)-1970-622-354
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  • Janet Taylor,

    1. Institute of Biological Sciences, Cledwyn Building, University of Wales, Aberystwyth, Ceredigion SY23 3DD, Wales, UK; telephone: +44-(0)-1970-621-947; fax: +44-(0)-1970-622-354
    2. Department of Computer Science, University of Wales, Aberystwyth, Ceredigion SY23 3DD, Wales, UK
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  • Naheed Kaderbhai,

    1. Institute of Biological Sciences, Cledwyn Building, University of Wales, Aberystwyth, Ceredigion SY23 3DD, Wales, UK; telephone: +44-(0)-1970-621-947; fax: +44-(0)-1970-622-354
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  • Michael K. Winson,

    1. Institute of Biological Sciences, Cledwyn Building, University of Wales, Aberystwyth, Ceredigion SY23 3DD, Wales, UK; telephone: +44-(0)-1970-621-947; fax: +44-(0)-1970-622-354
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  • David A. Small,

    1. Zeneca Bio Products, Billingham, Clevland, UK
    Current affiliation:
    1. Stiefel Laboratories (UK), Ltd., Maidenhead, Berkshire, UK
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  • Jem J. Rowland,

    1. Department of Computer Science, University of Wales, Aberystwyth, Ceredigion SY23 3DD, Wales, UK
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  • Douglas B. Kell,

    1. Institute of Biological Sciences, Cledwyn Building, University of Wales, Aberystwyth, Ceredigion SY23 3DD, Wales, UK; telephone: +44-(0)-1970-621-947; fax: +44-(0)-1970-622-354
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  • Royston Goodacre

    Corresponding author
    1. Institute of Biological Sciences, Cledwyn Building, University of Wales, Aberystwyth, Ceredigion SY23 3DD, Wales, UK; telephone: +44-(0)-1970-621-947; fax: +44-(0)-1970-622-354
    • Institute of Biological Sciences, Cledwyn Building, University of Wales, Aberystwyth, Ceredigion SY23 3DD, Wales, UK; telephone: +44-(0)-1970-621-947; fax: +44-(0)-1970-622-354
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Abstract

Two rapid vibrational spectroscopic approaches (diffuse reflectance–absorbance Fourier transform infrared [FT-IR] and dispersive Raman spectroscopy), and one mass spectrometric method based on in vacuo Curie-point pyrolysis (PyMS), were investigated in this study. A diverse range of unprocessed, industrial fed-batch fermentation broths containing the fungus Gibberella fujikuroi producing the natural product gibberellic acid, were analyzed directly without a priori chromatographic separation. Partial least squares regression (PLSR) and artificial neural networks (ANNs) were applied to all of the information-rich spectra obtained by each of the methods to obtain quantitative information on the gibberellic acid titer. These estimates were of good precision, and the typical root-mean-square error for predictions of concentrations in an independent test set was <10% over a very wide titer range from 0 to 4925 ppm. However, although PLSR and ANNs are very powerful techniques they are often described as “black box” methods because the information they use to construct the calibration model is largely inaccessible. Therefore, a variety of novel evolutionary computation-based methods, including genetic algorithms and genetic programming, were used to produce models that allowed the determination of those input variables that contributed most to the models formed, and to observe that these models were predominantly based on the concentration of gibberellic acid itself. This is the first time that these three modern analytical spectroscopies, in combination with advanced chemometric data analysis, have been compared for their ability to analyze a real commercial bioprocess. The results demonstrate unequivocally that all methods provide very rapid and accurate estimates of the progress of industrial fermentations, and indicate that, of the three methods studied, Raman spectroscopy is the ideal bioprocess monitoring method because it can be adapted for on-line analysis. © 2002 Wiley Periodicals, Inc. Biotechnol Bioeng 78: 527–538, 2002.

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