title: Effect of an exponential feeding regime on the production of Rhodotorula araucariae epoxide hydrolase in Yarrowia lipolytica.
abstract: OBJECTIVE
  To evaluate the effect of and exponential feeding regime on the production of epoxide hydrolase (EH) enzyme in recombinant Yarrowia lipolytica in comparison to a constant feed strategy.
  
  
  RESULTS
  An exponential feed model was developed and fermentations were fed at six different exponential rates. A twofold increase in EH productivity and a 15% increase in volumetric EH activity was obtained by applying exponential glucose feed rates in fed-batch cultivation. These responses were modelled to obtain a theoretical optimum feed rate that was validated in duplicate fermentations. The model optimum of 0.06 h(-1) resulted in a volumetric EH activity of c. 5500 U l(-1) h(-1) and a maximum activity of 206,000 U l(-1). This correlated well with model predictions, with a variance of <10%.
  
  
  CONCLUSIONS
  The use of an exponential feed strategy at a rate of 0.06 h(-1) yielded best results for all key responses which show a clear improvement over a constant feed strategy.
  
  
  CONCLUSIONS
  The study was the first evaluation of an exponential feed strategy on recombinant Y. lipolytica for the production of EH enzyme. The results suggest a strategy for the commercial production of a valuable pharmaceutical enzyme.
authors.affiliation: CSIR Biosciences, Modderfontein, Gauteng, South Africa. dmaharajh@csir.co.za
authors.forename: D
authors.initials: D
authors.lastname: Maharajh
authors.forename: R
authors.initials: R
authors.lastname: Lalloo
authors.forename: J
authors.initials: J
authors.lastname: Görgens
mesh_terms: D019149:Bioreactors / Q000382:microbiology; D004851:Epoxide Hydrolases / Q000235:genetics / Q000378:metabolism*; D005285:Fermentation; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism*; D007218:Industrial Microbiology / Q000379:methods*; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D012248:Rhodotorula / Q000201:enzymology*; D025062:Yarrowia / Q000235:genetics / Q000378:metabolism*
chemical_list: D005656:Fungal Proteins; D011994:Recombinant Proteins; D004851:Epoxide Hydrolases