Gene FliC coding for flagellin FliC of Salmonella enterica serovar Typhimurium was expressed in Escherichia coli BL21 in the fusion form with chickens' immunopotentiator-thioredoxin (Trx), thus the recombinant protein was abbreviated to TrxFliC. In order to have a large amount of the recombinant antigen for Salmonella vaccine or vaccine adjuvant developments, in this study, some fermentation parameters and procedure were investigated in multi-parallel fermentation system Greta (Sweden). In the bioreactors, nutrient in medium and fermentation process played an important role in E. coli BL21 cells mass and TrxFliC yield. Fed-batch fermentation by adding one dose of YTG (yeast extract, tryptone and glycerol) following the first batch fermentation, the cell mass increased quickly, volumetric productivity of TrxFliC reached over 1.8 g/l, correlate to 0.14 g/g dry cell mass. However, fed-batch fermentation by combining addition of one dose of nutrient then by nutrient exponential feed increased significantly TrxFliC productivity. Point of time for adding IPTG to induce recombinant protein production was an important parameter. For obtaining a huge of TrxFliC, IPTG should be added during fed-batch fermentation when OD600 reached approximately 24. During fed-batch with exponential feed, nutrient impacted in TrxFliC stability. Productivity of TrxFliC was lower when the recombinant strain was exponentially fed with YTG or glycerol, however the TrxFliC yield was gained more stable when the producer strain was exponential fed with YG (glycerol and yeast extract). In the optimal fermentation conditions and parameters, the obtained yield of TrxFliC was 4.6 g/l culture, increased 9 times if comparing to TrxFliC productivity in the flask fermentation.
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