Enhancement of human granulocyte-colony stimulating factor production in recombinant E. coli using batch cultivation

Development of inexpensive and simple culture media is always favorable for recombinant protein over-expression in E. coli. The effects of medium composition on the production of recombinant human granulocyte-colony stimulating factor (rh-GCSF) were investigated in batch culture of E. coli BL21 (DE3) [pET23a-hgcsf]. First, the optimum medium for production of rh-GCSF was determined; and, then it was shown that mixture of amino acid addition at induction time, which was determined on the basis of amino acids frequency in the recombinant protein, increases recombinant protein expression level significantly. Furthermore, the effect of glucose concentration on productivity of rh-GCSF was investigated; 20 g/l of glucose will result in maximum attainable biomass and rh-GCSF in this process. At optimum conditions, a cell dry weight of 10.5 g/l, an expression level of about 35% of total cellular protein, rh-GCSF concentration of 1.75 +/- 0.1 g/l, and overall rh-GCSF yield of 165 +/- 5 mg/g were obtained.