Parallel factor analysis combined with PLS regression applied to the on-line monitoring of Pichia pastoris cultures
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Various key variables (biomass, substrate and product) of bioprocesses should be monitored in order to retrieve useful information on the system, with the biomass (the cell density) the principal target. Although several analytical methods have been adapted and used to monitor the evolution of cell density evolution in cultures, a general method for performing this determination has not yet been established, as each technique has its own advantages and drawbacks. In the present work, noninduced glycerol batch cultures (for which biomass and substrate are the key variables) were monitored using multiwavelength fluorescence spectroscopy. The data gathered were modelled via PARAFAC-PLS chemometric methodologies, resulting in important qualitative and quantitative information about the behaviours of different biogenic fluorophors in batch cultures of the yeast Pichia pastoris. This information was used to predict the target process variables in such cultures; this permitted the applicability of this combined technique to bioprocess monitoring to be assessed.
KeywordsPARAFAC PLS Pichia pastoris Biomass monitoring On-line monitoring
This work has been supported by the Spanish Programme of Chemical Processes Technologies (projects CTQ 2004-02013 and CTQ 2004-00300). The authors would like to thank Thomas Scheper’s group (Institut für Technische Chemie, Universität Hannover) for the support received with all of the on-line fluorescence data presented in this work.
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