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Fermentation and oxygen transfer characteristics in recombinant human growth hormone production by Pichia pastoris in sorbitol batch and methanol fed‐batch operation

2009; Wiley; Volume: 85; Issue: 2 Linguagem: Inglês

10.1002/jctb.2292

1097-4660

Pınar Çalı́k, Bahar İnankur, Elif Ş. Soyaslan, Merve Şahin, Hatice Taşpınar, Eda Açık, Eda Bayraktar,

Fungal and yeast genetics research

Abstract BACKGROUND: The influence of methanol feed rate on recombinant human growth hormone (rhGH) production by Pichia pastoris hGH‐Mut + in medium containing sorbitol was investigated at three different specific growth rates (µ), namely, 0.02 (MS‐0.02), 0.03 (MS‐0.03), and 0.04 (MS‐0.04). RESULTS: Increasing methanol feed rate above MS‐0.03 did not affect sorbitol consumption, showing that µ = 0.03 h −1 is a threshold limiting value, above which sorbitol utilization became independent of methanol feed rate. Moreover, when sorbitol was consumed, no further cell growth was observed. Increase in methanol feed rate triggered cell synthesis and the highest cell concentration was obtained at MS‐0.04 as 48 g L −1 ( t = 18 h); whereas, the highest rhGH production, 270 mg L −1 , was obtained at MS‐0.03 as a consequence of lower extracellular protease production and higher AOX activity (41 U g −1 CDW). Oxygen uptake rate increased with increasing µ, having the maximum value, 76.6 mmol m −3 s −1 , at MS‐0.04. K L a had a tendency to increase with µ, having a maximum value of 0.15 s −1 at MS‐0.04 ( t = 15 h). CONCLUSION: By considering rhGH concentration and oxygen transfer characteristics, the bioprocess can be improved by a two‐stage feeding strategy, operating at MS‐0.04 at the beginning of fermentation, and thereafter shifting to MS‐0.03. Copyright © 2009 Society of Chemical Industry