A Simple Method to Reduce both Lactic Acid and Ammonium Production in Industrial Animal Cell Culture

Abstract

Fed-batch animal cell culture is the most common method for commercial production of recombinant proteins. However, higher cell densities in these platforms are still limited due to factors such as excessive ammonium production, lactic acid production, nutrient limitation, and/or hyperosmotic stress related to nutrient feeds and base additions to control pH. To partly overcome these factors, we investigated a simple method to reduce both ammonium and lactic acid production-termed Lactate Supplementation and Adaptation (LSA) technology-through the use of CHO cells adapted to a lactate-supplemented medium. Using this simple method, we achieved a reduction of nearly 100% in lactic acid production with a simultaneous 50% reduction in ammonium production in batch shaker flasks cultures. In subsequent fed-batch bioreactor cultures, lactic acid production and base addition were both reduced eight-fold. Viable cell densities of 35 million cells per mL and integral viable cell days of 273 million cell-days per mL were achieved, both among the highest currently reported for a fed-batch animal cell culture. Investigating the benefits of LSA technology in animal cell culture is worthy of further consideration and may lead to process conditions more favorable for advanced industrial applications.

Keywords: ammonium; animal cell culture; fed-batch; industrial; lactic acid; recombinant proteins.

Figure 1

Specific net growth rate in lactate-supplemented medium as a function of adaptation time for batch shaker flask cultures.

Figure 2

Effect of initial lactate concentration on specific lactic acid production rate in batch shaker flask cultures.

Figure 3

Viable cell concentrations for fed-batch bioreactor cultures.

Figure 4

Viabilities for fed-batch bioreactor cultures.

Figure 5

l-lactate levels for fed-batch bioreactor cultures.

Figure 6

Specific lactic acid production rates for fed-batch bioreactor cultures.

Figure 7

Glucose levels for fed-batch bioreactor cultures.

Figure 8

Specific glucose consumption rates for fed-batch bioreactor cultures.

Figure 9

pH levels for fed-batch bioreactor cultures.

Figure 10

Base addition volumes for fed-batch bioreactor cultures.

Figure 11

Osmolality levels for fed-batch bioreactor cultures.

Figure 12

Ammonium levels for fed-batch bioreactor cultures.

Figure 13

Specific ammonium production rates for fed-batch bioreactor cultures.