November 1-5, 2015
The interest in use perfusion mode has increased in the last years, due to an increased awareness of perfusion advantages, some general improvement in equipment reliability, and a broadening of operational skills in the biomanufacturing industry. However, mathematical modeling of bioreactors in continuous mode with cell retention (perfusion mode) with concomitant cell bleeding is still emerging, because this scheme has a few applications in global biotechnology industry. The case of study was industrial fermentation process of CHO cells producing EPO-hr. The model involves a total of 7 equations and 19 variables. In order to fix the degrees of freedom were obtained experimentally from batch culture the kinetics parameters using logistic equations and was fixed operational parameters. It was determined that glutamine is limiting substrate and is related to specific growth rate through the model proposed by Monod. Validation of model was done by comparing different steady states with predicted values. On the other hand, a sensitivity analysis of the kinetic parameters and the influence of design and operating variables was performed. The variables with major impacts (up 2.5 fold) in volumetric productivity were concentration factor R and dilution rate D (Figures 1 and 2).
Nevertheless a technological limitation for the perfusion equipment used was identify (Figure 3), for that reason another apparatus must be evaluate.
It was further determined that optimum value of volumetric productivity can be reached is 4.5 fold, which is reached at a dilution rate (D) of 2.37 vvd and a concentration factor of 1.91. The feeding strategy could be works at 0.7 vvd with glutamine concentrated 2.55 fold.
Osman Fernandez, Raydel Alvarez, Ernesto Chico, Adolfo Castillo, and Julio Dustet, "Mathematical modeling of a bioreactor producing Epo-hr operating in perfusion mode" in "Integrated Continuous Biomanufacturing II", Chetan Goudar, Amgen Inc. Suzanne Farid, University College London Christopher Hwang, Genzyme-Sanofi Karol Lacki, Novo Nordisk Eds, ECI Symposium Series, (2015). http://dc.engconfintl.org/biomanufact_ii/123