The perfusion medium is critical in maintaining high cell concentration in cultures for the production of monoclonal antibody by Chinese hamster ovary cells. In this study, the effects of perfusion culture strategies when using different media on the process stability, product titer, and product quality were investigated in 3-L bioreactor. The results indicated that continuous perfusion could maintain higher levels of cell density, product titer, and quality in comparison with those of the intermittent perfusion culture. Next, the perfusion culture conditions with different perfusion rates and temperature reduction methods were further optimized. When combining the high perfusion rates and delayed reduction of culture temperature at day 6, the product titer reached a higher level of 16.19 g/L with the monomer relative abundant of 97.6%. In this case, the main peak of the product reached 56.3% and the total N-glycans ratio was 95.2%. To verify the effectiveness of the optimized perfusion culture in a larger scale, a 200-L bioreactor was used to perform and the final product titer reached the highest level of 16.79 g/L at day 16. Meanwhile, the product quality (monomer abundant of 97.6%, main peak of 56.3%, and N-glycans ratio of 96.5%) could also be well maintained. This study provided some guidance for the high-efficient production of monoclonal antibody by CHO cells via optimized perfusion culture strategy.
In production of porcine interferon α (pIFN-α) by Pichia pastoris, improper glycerol feeding strategy leads to ethanol accumulation in the last stage of growth phase. In the present study, taking two runs with low ethanol accumulation under 2 g/L as control group, effects of long-term (>4 h) and instantaneous high ethanol concentration (>10 g/L) on pIFN-α production, and activities of key enzymes in carbon metabolism were discussed. As a result, compared with control group, pIFN-α expression level was decreased about 4~12 folds under long-term high ethanol concentration, from the level above 3 g/L to the level under 1 g/L; pIFN-α expression level was decreased about 8 folds under instantaneous high ethanol concentration, reaching to the low level of 0.42 g/L. The low production of pIFN-α was caused by the severe inhibitory effect of ethanol on these enzymes.
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