Shinjiro Yamamoto

Aggregate formation of rCHO cells and its maintenance in repeated batch culture in the absence of cell adhesion materials.

Aggregate formation of recombinant Chinese hamster ovary (rCHO) cells capable of producing granulocyte colony-stimulating factor (G-CSF), using medium lacking cell adhesion materials in a repeated batch culture, was examined together with cell growth, cell viability and G-CSF production. The rCHO culture was conducted in a rotary shaker and the medium was changed every five days. The formation of stable cell aggregates with high reproducibility was observed after the first medium change. The size of the cell aggregates (consisting of several 10s to 40,000 cells) formed during the repeated batch culture ranged from 30 to 600 microm. The cell density of the aggregates reached as high as 2 x 10(6) cells/ml and the viability was maintained at more than 80% for 19 d. Changing the medium to avoid glucose exhaustion effectively maintained the cell density, cell viability and G-CSF productivity at high levels.

Enhancement of autotrophic growth rate ofAlcaligenes eutrophus in a medium containing perfluorocarbon under low oxygen partial pressure

SummaryUnder low oxygen partial pressure,Alcaligenes eutrophus was cultivated autotrophically in a medium containing perfluorocarbon (PFC) as an oxygen-carrier. In the presence of PFC of more than 70% of the medium volume, enhancement of the growth rate was observed. At 90% PFC, the rate was about 18 times greater than that at 0% PFC.

Process Simulation of Desulfurization from Pyrite by Thiobacillus ferrooxidans in a Packed-Bed Medium-Recirculating Bioreactor under Different Recirculation Rates

Abstract Effect of medium-recirculation rate on desulfurization of pyrite by Thiobacillus ferrooxidans in a packed-bed bioreactor was examined for developing an efficient on-site desulfurization process of low grade coal. Linear relationship between elution rate of SO 4 2- and oxygen supply rate indicated that desulfurization rate was limited by dissolved oxygen (DO) supply which was dependent on the recirculation rate. Based on these results, a mathematical model consisting of DO limitation and product inhibition was constructed and satisfactorily simulated the performance in the on-site type desulfurization process.