Studies On The Optimal Process Conditions Of Recombinant Human Interleukin-11 Expressed By Pichia Pastoris

Chemotherapy induced thrombocytopenia can be treated by recombinant human interleukin eleven（rhIL-11）.Commercially available rhIL-11 is produced by the traditional method with engineered Escherichia coli expressing rhIL-11 as a fusion protein.Its down-stream purification processing is very complicated,and the cost is high.Facing on the fierce competition in markets,improvement of the production technology is very useful and urgent.To save the cost and improve the batch yield in the process,we constructed the rhIL-11 expressing Pichia pastoris strain which is easy to operate with low cost,and the studies on the optimal process conditions of recombinant human interleukin-11 expressed by Pichia pastoris were carried out.Using the recombined Pichia pastoris strain,the fermentation and purification process conditions were investigated.Effects of cultivation conditions such as temperature,pH and methanol induced concentrations on shake flask cultivation of recombined Pichia pastoris strain were investigated.And optimal incubation conditions were obtained.On the base of the previous studies,expression of rhIL-11 protein in 15 liters automatic fermentation tank was studied using the recombinant Pichia pastoris.The optimal conditions of induce starting point(initial OD₆₀₀ before inducation),induce time,dissolved oxygen （DO）,culture medium and methanol induced mode were optimized.The target protein productivity level could be improved up to 30-40%under the optimal fermentation conditions compared with unoptimized conditions.Then,the purification processdures were also investigated. Different chromatography media,salt concentration,linear flow rate and elution condition were selected,the recovery rate of rhIL-11 protein were significantly improved.The target protein yield of purification can be improved up to 62.8%with no change of product quality.At last,the optimal process conditions of recombinant human interleukin-11 have finished by three batchs,and the yield can be improved up to 90.7%.