Anaerobic fermentation of xylose by pichia stipitis: The effect of forced cycling of ph

Authors

  • Per-Ola Ryding,

    1. Department of Chemical Reaction Engineering, Chalmers University of Technology, S-412 96 Göteborg, Sweden
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  • Claes Nlklasson,

    1. Department of Chemical Reaction Engineering, Chalmers University of Technology, S-412 96 Göteborg, Sweden
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  • Gunnar Lidén

    Corresponding author
    1. Department of Chemical Reaction Engineering, Chalmers University of Technology, S-412 96 Göteborg, Sweden
    • Department of Chemical Reaction Engineering, Chalmers University of Technology, S-412 96 Göteborg, Sweden
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Abstract

Xylose fermentation by Pichia stipitis was examined using a two-stage batch process. The cells were first grown aerobically on D-xylose (5 g/L), whereafter additional xylose (10 g/L) was added and fermented during anaerobic conditions (T=30°C). The optimum pH value for a fermentation with constant pH was found to be 4.5 (maximum specific ethanol production rate 0.21 g/(g h). Forced square wave cycling of the pH between 4 and 5, and 3.5 and 5.5 (cycle time 30 min) during the fermentation stage resulted in a fermentation rate lower than the maximum rate, but with unchanged ethanol yields.

Abstract

On a étudié la fermentation du xylose par Pichia stipitis à l'aide d'un procédé discontinu biétagé. On a d'abord fait croǐtre les cellules en condition aérobique sur du D-xylose (5 g/L), auquel a été rajouté du xylose (I0 g/L) qu'on a laissté fermenter en condition anaérobique (T=30°C). On a trouvé que la valeur de pH optimale pour une fermentation à pH constant était de 4,5 (vitesse de production d'éthanol spécifique maximale de 0,21 g/(g h). Le cyclage par ondes carrées forcé du pH entre 4 et 5 et entre 33 et 53 (durée du cycle de 30 min) à l'étape de la fermentation entraǐne une vitesse de fermentation inférieure à la vitesse maximale, les rendements en éthanol demeurant toutefois inchangés.

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