GROWTH KINETICS AND HUMAN GROWTH HORMONE PRODUCTION OF A HEAT- INDUCIBLE RECOMBINANTE CHERICHIA COLI DURING BATCH FERMENTATION

Abstract

The batch fermentation production of human growth hormone (hGH) was studied in a newrecombinant Escherichia coli. The effect of different levels of dissolved oxygen and glucoseconcentration on cell density and substrate utilization were evaluated. The results indicated that theoptimum level of dissolved oxygen was 25% of air saturation. The specific growth rate reached amaximum for an optimal glucose concentration of 5 gl-1, the maximum yield was 0.58 gg-1 and glucosewas completely consumed after 10 hrs. The growth of recombinant E. coli on semi-defined and complexmedia was compared. The results demonstrated that dry cell weight and maximum specific growth ratewere 2.35 gl-1 and 0.4 h-1 on a complex medium, respectively, but they were 3.3 gl-1 and 0.24 h-1 onsemi-defined medium. The plasmid stability and hGH production during batch fermentation wereinvestigated. The results suggested that the specific growth rate is the most important factor on hGHproduction and should be investigated in fed batch cultivation to get high cell density.