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Open Access research with a European policy impact...

The Strathprints institutional repository is a digital archive of University of Strathclyde's Open Access research outputs. Strathprints provides access to thousands of Open Access research papers by Strathclyde researchers, including by researchers from the European Policies Research Centre (EPRC).

EPRC is a leading institute in Europe for comparative research on public policy, with a particular focus on regional development policies. Spanning 30 European countries, EPRC research programmes have a strong emphasis on applied research and knowledge exchange, including the provision of policy advice to EU institutions and national and sub-national government authorities throughout Europe.

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Morphological and enzymatic responses of a recombinant aspergillus niger to oxidative stressors in chemostat cultures

Kreiner, M. and Harvey, L.M. and McNeil, B. (2003) Morphological and enzymatic responses of a recombinant aspergillus niger to oxidative stressors in chemostat cultures. Journal of Biotechnology, 100 (3). pp. 251-260. ISSN 0168-1656

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Abstract

Continuous chemostat cultures of a recombinant strain of Aspergillus niger (B1-D), engineered to produce the marker protein hen egg white lysozyme, were investigated with regard to their susceptibility to oxidative stress. The culture response to oxidative stress, produced either by addition of exogenous hydrogen peroxide (H2O2) or by high dissolved oxygen tension (DOT), was characterised in terms of the activities of two key defensive enzymes: catalase (CAT) and superoxide dismutase (SOD). Since the morphology is so critical in submerged fungal bioprocesses, the key morphological indices were analysed using a semi-automated image analysis system. Both oxidant stressors, H2O2 and elevated DOT, increased both enzyme activities, however, the extent was different: exogenous H2O2 led mainly to increased CAT activity, whereas gassing with O2 enriched air, which resulted in a DOT of 165% of air saturation, increased both enzyme activities more than 2-fold compared with the control steady state culture. Addition of exogenous H2O2 resulted in shorter hyphae compared with control steady state cultures. These findings indicate that it is unsound to use exogenous H2O2 to simulate oxidative stress induced by elevated dissolved oxygen levels since the response to each might be quite different, both in terms of enzymatic (defensive) responses and in terms of culture morphology.