Production of alginate by Azotobacter vinelandii grown at two bioreactor scales under oxygen-limited conditions

ALVARO ENRIQUE DIAZ BARRERA, Javiera Gutierrez, Fabiola Martínez, CLAUDIA VICTORIA ALTAMIRANO GOMEZ

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12 Scopus citations

Abstract

The oxygen transfer rate (OTR) was evaluated as a scale-up criterion for alginate production in 3- and 14-L stirred fermentors. Batch cultures were performed at different agitation rates (200, 300, and 600 rpm) and airflow rates (0.25, 0.5, and 1 vvm), resulting in different maximum OTR levels (OTR max ). Although the two reactors had a similar OTR max (19 mmol L -1 h -1 ) and produced the same alginate concentration (3.8 g L -1 ), during the cell growth period the maximum molecular weight of the alginate was 1,250 kDa in the 3-L stirred fermentor and 590 kDa in 14-L stirred fermentor. The results showed for the first time the evolution of the molecular weight of alginate and OTR profiles for two different scales of stirred fermentors. There was a different maximum specific oxygen uptake rate between the two fermenters, reaching 8.3 mmol g -1 h -1 in 3-L bioreactor and 10.6 mmol g -1 h -1 in 14-L bioreactor, which could explain the different molecular weights observed. These findings open the possibility of using qO 2 instead of OTR max as a scaling criterion to produce polymers with similar molecular weights during fermentation.

Original languageEnglish
Pages (from-to)1133-1140
Number of pages8
JournalBioprocess and Biosystems Engineering
Volume37
Issue number6
DOIs
StatePublished - 1 Jan 2014

Keywords

  • Alginate
  • Molecular weight
  • Oxygen transfer rate
  • Scale-up
  • Stirred fermentor

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