Maharajh_2008_Lett.Appl.Microbiol_47_520

AIMS: 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. METHODS AND 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. SIGNIFICANCE AND IMPACT OF THE STUDY: 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.