Kinetic Modeling of Cell Growth and Product Formation in Submerged Culture of Recombinant Aspergillus nigeu

The kinetics of cell growth and protein production for the recombinant Aspergillus niger strain AB4.l(pgpdAGLAGFP]#II were investigated. An zcnstructured kinetic model was developed to describe the cell grolvth and product formation nmtl~enzatically. The dynamics of glucose consumption and biomass production can be I$-ell-described by the model. The asstcmption that the degradation of GFP by proteases is a first-order reaction can express the trend of the GFP profile reasonably well. The dynamics of protease prodzcction is also described reasonably well by considering the inhibition effect of glucose on protease production. Becazcse of the high initiul glz~cose concentration and keeping the pH value of the broth at 6, the protease activity could be kept low most of the time during the fermentation. The increase of protease activity near the end of the culture might be catcsed by cell lysis because the intracell~clar protease activity was much higher than the extracellular activity.