Dependence of morphology on agitation intensity in fed-batch cultures of Aspergillus oryzae and it implications for recombinant protein production

A Amanullah, K Christensen, K Hansen, Alvin Nienow, Colin Thomas

Research output: Contribution to journalArticle

77 Citations (Scopus)

Abstract

We previously reported that, although agitation conditions strongly affected mycelial morphology, such changes did not lead to different levels of recombinant protein production in chemostat cultures of Aspergillus oryzae (Amanullah et al., 1999). To extend this finding to another set of operating conditions, fed-batch fermentations of A. oryzae were conducted at biomass concentrations up to 34 g dry cell weight/L and three agitation speeds (525, 675, and 825 rpm) to give specific power inputs between 1 and 5 kWm(-3). Gas blending was used to control the dissolved oxygen level at 50% of air saturation except at the lowest speed where it fell below 40% after 60-65 h. The effects of agitation intensity on growth, mycelial morphology, hyphal tip activity, and recombinant protein (amyloglucosidase) production in fed-batch cultures were investigated. In the batch phase of the fermentations, biomass concentration, and AMG secretion increased with increasing agitation intensity. If in a run, dissolved oxygen fell below approximately 40% because of inadequate oxygen transfer associated with enhanced viscosity, AMG production ceased. As with the chemostat cultures, even though mycelial morphology was significantly affected by changes in agitation intensity, enzyme titers (AGU/L) under conditions of substrate limited growth and controlled dissolved oxygen of >50% did not follow these changes. Although the measurement of active tips within mycelial clumps was not considered, a dependency of the specific AMG productivity (AGU/g biomass/h) on the percentage of extending tips was found, suggesting that protein secretion may be a bottle-neck in this strain during fed-batch fermentations.
Original languageEnglish
Pages (from-to)815-826
Number of pages12
JournalBiotechnology and Bioengineering
Volume77
Issue number7
Early online date28 Jan 2002
DOIs
Publication statusPublished - 30 Mar 2002

Keywords

  • recombinant protein
  • agitation intensity
  • fed-batch fungal fermentations
  • mycelial morphology
  • hyphal tip activity

Fingerprint

Dive into the research topics of 'Dependence of morphology on agitation intensity in fed-batch cultures of Aspergillus oryzae and it implications for recombinant protein production'. Together they form a unique fingerprint.

Cite this