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Parallel Bubble Columns with Fed‐Batch Technique for Microbial Process Development on a Small Scale
Author(s) -
AltenbachRehm J.,
Nell Ch.,
Arnold M.,
WeusterBotz D.
Publication year - 1999
Publication title -
chemical engineering and technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.403
H-Index - 81
eISSN - 1521-4125
pISSN - 0930-7516
DOI - 10.1002/(sici)1521-4125(199912)22:12<1051::aid-ceat1051>3.0.co;2-c
Subject(s) - lac operon , chemistry , industrial fermentation , chromatography , inducer , volume (thermodynamics) , bioreactor , continuous stirred tank reactor , fermentation , substrate (aquarium) , analytical chemistry (journal) , escherichia coli , biochemistry , organic chemistry , thermodynamics , biology , gene , ecology , physics
12 small‐scale bubble columns, each and every column with a total volume of 500 ml, individually controlled distribution of sterile and humidified air and a pH‐probe, were operated in an incubation chamber with temperature control. Intermittent feeding of substrate or inducer, as well as of base for parallel pH‐control was achieved by connecting a precision syringe pump to a valve distributor with one 2/2‐way miniature valve for each bubble column. This new parallel bio‐reactor technique was applied for optimization of the feed profile of the chemical inducer isopropyl‐β‐D‐thiogalactoside (IPTG) to improve the expression of a foreign protein (guanosin‐5′‐diphosphate‐α‐D‐mannose‐pyrophosphorylase, GDP‐manPP) under the control of the lac promoter in Escherichia coli . A mean cell density of 8 g l –1 of recombinant E. coli was achieved in parallel fed‐batch fermentations within 9.5 h due to a sufficient oxygen transfer ( k L a of up to 0.2 s –1 ) and parallel pH‐control. The GDP‐manPP activity was improved by more than 100 % compared to the standard IPTG pulse within 3 sets of parallel fed‐batch fermentations. A Genetic Algorithm was used for optimization of the IPTG feed profile. Scale‐up of the optimized fed‐batch process into the stirred tank reactor (scale‐up factor of 20) was possible, if all reaction conditions were copied exactly with respect to the reactor volume. A final GDP‐manPP activity of 715 U l –1 was measured 3 h after IPTG induction was finished.