Effects of initial ammonium ion concentration on pullulan production by Aureobasidium pullulans and its modeling
Journal
Journal of Food Engineering
Journal Volume
103
Journal Issue
2
Pages
115-122
Date Issued
2011
Author(s)
Abstract
Pullulan fermentations by Aureobasidium pullulans with various initial ammonium ion concentrations were evaluated in a 2-L bioreactor. The results demonstrated that A. pullulans produced highest pullulan (23.1 g/L) when the initial ammonium sulfate was 7 at 5 g/L. The purity of produced pullulan was 94.6%. Seven gram per liter of ammonium sulfate produced more biomass due to the higher level of nitrogen source, but the pullulan-degrading enzyme activity was detected after the depletion of sucrose, which reduced pullulan concentration. From the results of fed-batch fermentation, addition of 10 g/L of sucrose suppressed A. pullulans from producing pullulan-degrading enzyme. Additionally, the modified-Gompertz equation demonstrated its generality to fit all pullulan production, biomass production, and sucrose consumption curves at three ammonium sulfate levels. After incorporating the degrading factor, a re-modified-Gompertz equation was obtained that can adequately describe the decrease of pullulan at the late fermentation stage. ? 2010 Elsevier Ltd. All rights reserved.
Subjects
Aureobasidium pullulans
Fermentation
Gompertz equation
Modeling
Pullulan
Pullulanase
Type
journal article