A model for micro/ultrafiltration cell deactivation in cell-recycle reactors

Mechanical stress due to micro/ultrafiltration has been suggested by a numb er of authors as one of the sources for cell deactivation in continuous cel l-recycle reactors. This work introduces cell deactivation in the modelling of cell-recycle fermenters. A two-population based model is used. It is sh own that the kinetic parameters obtained from chemostat fermentations descr ibe accurately the experimental results and the apparent deviations to the Luedeking-Piret relationship at low growth rates are explained. The model i s applied to the data of two authors with dilution rates (D) ranging 0.2 an d 1.05h(-1) and using either Lactobacillus rhamnosus or Lactococcus cremori s cells. Although only data for lactic fermentation were used, the proposed model is of general applicability and not restricted to a type of fermenta tion, a given apparatus configuration or Newtonian fluids. The development of improved procedures for biological reactor modelling, such as presented in this work, wall allow more adequate and efficient design and operation o f these reactors. (C) 2000 Society of Chemical Industry.