Investigation of the Complex Culture Medium Composition for Improved Production of ONTAK Immunotoxin by Recombinant Escherichia Coli

In recent years, the biological methods have been considered as a most promising candidate for the cancer treatment. One of the most applicable methods is recombinant proteins. ONTAK immunotoxin is a special drug for cancer therapy of leukemia, lymphoma and melanoma. With respect to the dramatic growth of cancer in today's society, production of recombinant protein drugs seems to be necessary. In this research, optimization of complex culture medium for the expression of ONTAK recombinant has been studied. In this experimental study, various concentrations of IPTG (Isopropyl Thiogalactopyranoside) were used as an inductor and the medium components and induction time optimized for expression of ONTAK immunotoxin. The cell concentration was measured by optical density at 600 nm and the protein expression levels were analyzed by SDS-PAGE gel. The modified complex culture medium containing: glucose 6 g/l; K2HPO4 12.5 g/l; KH2PO4 2.3 g/l; Yeast Extract 20 g/l; Tryptone 10 g/l; were determined as optimal medium. OD600nm=3.0 was determined as the best time for induction by IPTG at a concentration of 0.1mM. The maximum amount of the expression of the target protein was determined at OD600nm=5.5. The adding of additive carbon source (glucose) to the complex medium was caused a better ONTAK immunotoxin expression as compared with the amount of expression observed in LB medium. The amount of produced biomass on the optimized medium increased over 3.5 times in comparison to LB medium.