A single nutrient feed supports both chemically defined NS0 and CHO fed‐batch processes: Improved productivity and lactate metabolism

作者：Ningning Ma, JoAnn Ellet, Centy Okediadi, Paul Hermes, Ellen L. McCormick, Susan A. Casnocha · 发表于：Biotechnology Progress · 年份：2009 · DOI：10.1002/btpr.238 · 被引用次数：111 · 研究领域：Microbial Metabolic Engineering and Bioproduction、Viral Infectious Diseases and Gene Expression in Insects、Wastewater Treatment and Nitrogen Removal

A chemically defined nutrient feed (CDF) coupled with basal medium preloading was developed to replace a hydrolysate-containing feed (HCF) for a fed-batch NS0 process. The CDF not only enabled a completely chemically defined process but also increased recombinant monoclonal antibody titer by 115%. Subsequent tests of CDF in a CHO process indicated that it could also replace the hydrolysate-containing nutrient feed in this expression system as well as providing an 80% increase in product titer. In both CDF NS0 and CHO processes, the peak lactate concentrations were lower and, more interestingly, lactate metabolism shifted markedly from net production to net consumption when cells transitioned from exponential to stationary growth phase. Subsequent investigations of the lactate metabolic shift in the CHO CDF process were carried out to identify the cause(s) of the metabolic shift. These investigations revealed several metabolic features of the CHO cell line that we studied. First, glucose consumption and lactate consumption are strictly complementary to each other. The combined cell specific glucose and lactate consumption rate was a constant across exponential and stationary growth phases. Second, Lactate dehydrogenase (LDH) activity fluctuated during the fed-batch process. LDH activity was at the lowest when lactate concentration started to decrease. Third, a steep cross plasma membrane glucose gradient exists. Intracellular glucose concentration was more than two orders of m...