Effects of dissolved oxygen availability and culture biomass at induction upon the intracellular expression of monoamine oxidase by recombinant E. coli in fed batch bioprocesses

Voulgaris, Ioannis, Arnold, S. Alison, Speight, Robert, Harvey, Linda M. and McNeil, Brian (2011) Effects of dissolved oxygen availability and culture biomass at induction upon the intracellular expression of monoamine oxidase by recombinant E. coli in fed batch bioprocesses. Process Biochemistry, 46 3: 721-729. doi:10.1016/j.procbio.2010.11.019


Author Voulgaris, Ioannis
Arnold, S. Alison
Speight, Robert
Harvey, Linda M.
McNeil, Brian
Title Effects of dissolved oxygen availability and culture biomass at induction upon the intracellular expression of monoamine oxidase by recombinant E. coli in fed batch bioprocesses
Journal name Process Biochemistry   Check publisher's open access policy
ISSN 1359-5113
1873-3298
Publication date 2011-03
Year available 2011
Sub-type Article (original research)
DOI 10.1016/j.procbio.2010.11.019
Volume 46
Issue 3
Start page 721
End page 729
Total pages 9
Place of publication London, NW United Kingdom
Publisher Elsevier
Collection year 2012
Language eng
Formatted abstract
The effects of oxygen availability and induction culture biomass upon production of an industrially important monoamine oxidase (MAO) were investigated in fed-batch cultures of a recombinant E. coli. For each induction cell biomass 2 different oxygenation methods were used, aeration and oxygen enriched air. Induction at higher biomass levels increased the culture demand for oxygen, leading to fermentative metabolism and accumulation of high levels of acetate in the aerated cultures. Paradoxically, despite an almost eight fold increase in acetate accumulation to levels widely reported to be highly detrimental to protein production, when induction wet cell weight (WCW) rose from 100% to 137.5%, MAO specific activity in these aerated processes showed a 3 fold increase. By contrast, for oxygenated cultures induced at WCW's 100% and 137.5% specific activity levels were broadly similar, but fell rapidly after the maxima were reached. Induction at high biomass levels (WCW 175%) led to very low levels of specific MAO activity relative to induction at lower WCW's in both aerated and oxygenated cultures. Oxygen enrichment of these cultures was a useful strategy for boosting specific growth rates, but did not have positive effects upon specific enzyme activity. Based upon our findings, consideration of the amino acid composition of MAO and previous studies on related enzymes, we propose that this effect is due to oxidative damage to the MAO enzyme itself during these highly aerobic processes. Thus, the optimal process for MAO production is aerated, not oxygenated, and induced at moderate cell density, and clearly represents a compromise between oxygen supply effects on specific growth rate/induction cell density, acetate accumulation, and high specific MAO activity. This work shows that the negative effects of oxygen previously reported in free enzyme preparations, are not limited to these acellular environments but are also discernible in the sheltered environment of the cytosol of E. coli cells.
Keyword Fermentation
Oxidative stress
E. coli
Monoamine oxidase
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status Non-UQ

Document type: Journal Article
Sub-type: Article (original research)
Collection: Australian Institute for Bioengineering and Nanotechnology Publications
 
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Created: Thu, 12 Sep 2013, 09:33:59 EST by Cathy Fouhy on behalf of Aust Institute for Bioengineering & Nanotechnology