Methanol feeding strategy design enhances recombinant human growth hormone production byPichia pastoris

BACKGROUND The effects of designed methanol and co-substrate feeding strategies on fed-batch recombinant human growth hormone (rhGH) production by Pichia pastoris hGH-Mut+ were investigated. RESULTS The highest cell concentration was obtained as 157 g L−1 with the exponential feeding strategy where methanol was fed at a pre-calculated feeding rate based on pre-determined µ0 = 0.03 h−1, and mannitol concentration was kept constant at 50 g L−1 for t=0–6 h. The highest rhGH concentration was obtained as 1.3 g L−1 at t=54 h with the methanol-stat feeding strategy, where no co-substrate was used and the methanol concentration was kept at 5 g L−1 in the medium during the production phase. Thereafter, in another methanol-stat feeding strategy with pulse-fed sorbitol, the highest rhGH concentration was obtained as 1.2 g L−1 at t=42 h. CONCLUSION The methanol-stat fed-batch method keeping methanol concentration constant at 5 g L−1 in the production medium increased rhGH production at least 2-fold compared with that of the exponential feeding strategies. In the designed methanol-stat feeding strategies, use of sorbitol as co-substrate decreased methanol demand of the cells 2-fold, increased the overall product yield on the substrate 1.6-fold, shortened the cultivation time by 12 h and increased the productivity. Thus, methanol-stat feeding with co-substrate sorbitol was found to be a favorable fed-batch strategy for rhGH production by Pichia pastoris under alcohol oxidase I promoter. © 2014 Society of Chemical Industry