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

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.

ORCID iDs

Kreiner, M. ORCID: https://orcid.org/0000-0003-4824-0153

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  Item type:	Article
  ID code:	38423
  Dates:	Date Event 2003 Published
  Keywords:	aspergillus niger, oxidative stress, oxygen enrichment, hydrogen peroxide, superoxide dismutase, catalase, Pharmacy and materia medica, Applied Microbiology and Biotechnology, Biotechnology
  Subjects:	Medicine > Pharmacy and materia medica
  Department:	Faculty of Science > Strathclyde Institute of Pharmacy and Biomedical Sciences
  Depositing user:	Pure Administrator
  Date deposited:	12 Mar 2012 15:56
  Last modified:	20 Jan 2021 17:47
  URI:	https://strathprints.strath.ac.uk/id/eprint/38423