Evaluating kinetic and physiological features of rCHO-K1 cells cultured on microcarriers for production of a recombinant metalloprotease/disintegrin

We present kinetic and physiological data regarding the culturing of rCHO-K1 cells on various microcarriers, to evaluate the potential of this culture strategy for mass production of these cells and expression of a recombinant disintegrin. Cultures were performed in 500 mL spinner flasks in DMEM culture medium with 10 percent v/v fetal calf serum, gently shaken at 37 C, pH 7.4, in a 10 percent v/v CO2 atmosphere. The following values were obtained, respectively, for the adhesion time-constant Ka (h) and specific growth rate micron max (d-1) on each microcarrier: Cytodex 1 (0.91, 0.45), Cultispher S (0.28, 0.34), Immobasil FS (0.85, 0.52) and Pronectin F (5.12, 0.67). Metabolic characteristics showed some variation among the cultures with the four microcarriers, the most significant being the higher production of ammonia with microcarriers coated with adhesive molecules (Cultispher S and Pronectin F) relative to the uncoated carriers (Cytodex 1 and Immobasil FS). Experiments where the DMEM medium was gradually replaced by the serum-free medium (CHO-SFM-II) revealed important advantages over media containing serum, not only for assay purposes, but also for purification of the disintegrin. Altogether these results demonstrate that cultures on microcarriers, especially on Pronectin F, show good potential for larger scale cultures of rCHO-K1 cell.

Evaluation of the performance of a novel ceramic membrane bioreactor using the fungus Penicillium chrysogenum

The fungus Penicillium chrysogenum IFO-8644 was grown in a new type of ceramic membrane bioreactor operating with synthetic and complex germination medium at 27§C and pH7.0, using membranes with average pore diameters of 2.28 mm and effective area of 26.5 cm². Tests with different age inocula, an important factor in the development of the microorganisms, were performed. The best results were obtained using fresh inocula. Another extremely important factor to be considered in the desing of the bioreactor was the available membrane area for the growth of the fungus. As to the metabolism, sucrose was confirmed as the best source of carbon and energy since glucose had a repressive effect on the antibiotic production. A mathematical model, based on Monod growth kinetics for cell inhibition, enabled a reliable representation of the behavior of the bioreactor. Analysis of the experimental and simulated results showed that the bioprecess is viable in the novel bioreactor and that this bioreactor presents very promising potentials for large scale use.