Secretory Production of Human Growth Hormone in Escherichia coli in presence of lactose as inducer using pelB signal sequence

A gene encoding the mature form of the human growth hormone (hGH) was fused to the secretion signal coding sequence, pelB, this hybrid gene was expressed in E. coli under the transcriptional control of bacteriophage T7lac promoteoperator system. Studying the periplasmic protein pattern of the recombinant bacteria, showed that the recombinant bacteria allowed a partially succeeded secretion of hGH into the periplasmic space. Remaining of unprocessed pelB::hGH fusion-protein was also observed in the E. coli cytoplasmic space. Comparing to IPTG induction, we have also used lactose as natural inducer for over-expression of rhGH in the present system. Our results demonstrated that lactose is as effective as IPTG for inducing expression of recombinant hGH.