AMMONIA INHIBITION HYBRIDOMAS PROPAGATED IN BATCH, FED-BATCH, AND CONTINUOUS-CULTURE

The nature and temporal development of ammonia inhibition were investi gated in batch, fed-batch, and continuous cultures. Significant inhibi tion was observed when cells were inoculated in serum-containing or ch emically defined medium containing more than 2 mM of ammonia. In contr ast, no inhibition was observed at greater than 10 mM when the ammonia concentration was gradually increased over the span of a batch cultur e by feeding ammonium chloride. Strong growth inhibition was observed after each of five step changes (2.8 --> 3.7 --> 4.0 --> 4.9 --> 7.7 - -> 13.5 mM) in continuous culture. Following a period of adaptation at each higher value, the viable cell density stabilized at a new lower value. The lowering in viable cell density was caused by an increase i n specific death rate and a decreased cell yield on glucose, glutamine , and oxygen. Increased ammonia concentration had little or no effect on the steady-state specific growth kinetics or specific antibody prod uctivity. (C) 1994 John Wiley and Sons, Inc.