Oxygen transfer conditions in the production of rainbow trout growth hormone (rtGH) by Escherichia coli

Abstract

Batch cultures of Escherichia coli pRE1-rtGH 121/MZ1 were carried out at different oxygen transfer rates (OTR) enhanced by the increase of agitation and/or aeration rates. The growth kinetics of E. coli was investigated in complex medium under batch cultivation in 3 L fermenters. The agitation rates influenced both cell growth and rainbow trout growth hormone (rtGH) production in the bioreactor. It was found that increasing the agitation speed had a positive effect on the production of rtGH. Moreover, varying the airflow rate (vvm) in the fermentor under constant drive speed, cell growth and rtGH production were greatly influenced. In the production of rtGH by E. coli, high aeration rates were found to be essential for good yields of recombinant protein. Agitation speed and aeration rate could affect dissolved oxygen concentration, which in turn affected cell growth and rtGH production. Increased aeration rates induced higher rtGH production, with the highest concentration of 0.957 g/L obtained at 4.0 vvm, within 23 h. The highest volumetric productivity for rtGH of 0.042 g/L/h was obtained at both 1000 rpm and 4.0 vvm.