Methanol feeding strategy design enhances recombinant human growth hormone production by Pichia pastoris

ABSTRACT 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 µ 0 = 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