Abstract:
:A specially designed model reactor based on a 42-L laboratory fermentor was equipped with six stirrers (Rushton turbines) and five cylindrical disks. In this model reactor, the mixing time, Theta(90), turned out to be 13 times longer compared with the 42-L standard laboratory fermentor fitted with two Rushton turbines and four wall-fixed longitudinal baffles. To prove the suitability of the model reactor for scaledown studies of mixing-time-dependent processes, parallel exponential fed-batch cultivations were carried out with the leucine-auxotrophic strain, Corynebacterium glutamicum DSM 5715, serving as a microbial test system. L‐Leucine, the process-limiting substrate, was fed onto the liquid surface of both reactors. Cultivations were conducted using the same inoculum material and equal oxygen supply. The model reactor showed reduced sugar consumption (-14%), reduced ammonium consumption (-19%), and reduced biomass formation (-7%), which resulted in a decrease in L-lysine formation (-12%). These findings were reflected in less specific enzyme activity, which was determined for citrate synthase (CS), phosphoenolpyruvate carboxylase (PEP-C), and aspartate kinase (AK). The reduced specific activity of CS correlated with lower CO(2) evolution (-36%) during cultivation. The model reactor represents a valuable tool to simulate the conditions of poor mixing and inhomogeneous substrate distribution in bioreactors of industrial scale. Copyright 1999 John Wiley & Sons, Inc.
journal_name
Biotechnol Bioengjournal_title
Biotechnology and bioengineeringauthors
Schilling BM,Pfefferle W,Bachmann B,Leuchtenberger W,Deckwer Wdoi
10.1002/(sici)1097-0290(19990905)64:5<599::aid-bitsubject
Has Abstractpub_date
1999-09-05 00:00:00pages
599-606issue
5eissn
0006-3592issn
1097-0290pii
10.1002/(SICI)1097-0290(19990905)64:5<599::AID-BITjournal_volume
64pub_type
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