Effects of initial ammonium ion concentration on pullulan production by Aureobasidium pullulans and its modeling

Kuan Chen Cheng, Ali Demirci, Jeffrey M. Catchmark, Virendra M. Puri

Research output: Contribution to journalArticlepeer-review

24 Scopus citations

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.

Original languageEnglish (US)
Pages (from-to)115-122
Number of pages8
JournalJournal of Food Engineering
Volume103
Issue number2
DOIs
StatePublished - Mar 1 2011

All Science Journal Classification (ASJC) codes

  • Food Science

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