Influence of pH on recombinant human growth hormone production by Pichia pastoris |
| |
Authors: | P?nar Çal?k Eda Bayraktar Bahar ?nankur Elif ? Soyaslan Merve ?ahin Hatice Ta?p?nar Eda Aç?k Remziye Y?lmaz Tunçer H Özdamar |
| |
Affiliation: | 1. Department of Chemical Engineering, Industrial Biotechnology and Metabolic Engineering Laboratory, Middle East Technical University, 06531 Ankara, Turkey;2. Department of Biotechnology, Graduate School of Natural and Applied Sciences, Middle East Technical University, 06531 Ankara, Turkey;3. Equal contribution to this work.;4. Central Laboratory Biotechnology Unit, Middle East Technical University, 06531 Ankara, Turkey;5. Biochemical Reaction Engineering Laboratory, Chemical Engineering Department, Ankara University, Tando?an, 06100 Ankara, Turkey |
| |
Abstract: | BACKGROUND: Effect of pH on recombinant human growth hormone (rhGH) production by Pichia pastoris hGH‐Mut+ was investigated at pH = 4.2, 5.0, 5.5, and 6.0. RESULTS: The highest cell concentration was obtained at pH = 6.0 with 53 g L?1, while the highest rhGH concentration was attained at pH = 5.0 as 0.27 g L?1. Total protease secretion increased with increase in pH and with the cultivation time. Oxygen uptake rate increased with increasing pH up to pH = 6.0, having the maximum value, 37 mmol m?3 s?1, at pH = 5.5. KLa values were similar at all the conditions, having a maximum value of 0.14 s?1 at pH = 5.0. Taking the final rhGH concentration into account, the most favourable pH was 5.0; where AOX1 expression level showed a similar trend to AOX activity profiles, having the highest value of 9.4 × 1010 copy mg?1 CDW at t = 15 h; in parallel to AOX1 expression profile, hGH expression level increased until t = 15 h, with the highest value of 4.0 × 1010 copy mg?1 CDW, where a sharp increase in rhGH concentration was obtained. The expression levels of pep4, prb1 and prc1 genes, responsible from the production of proteinase A, proteinase B and, carboxypeptidase Y, were parallel to each other. CONCLUSION: Since it was shown that pH is a crucial operating parameter in fermentation processes using P. pastoris, keeping pH constant at its determined optimum value, pH = 5.0, during the bioprocess is vital in terms of recombinant protein production. Copyright © 2010 Society of Chemical Industry |
| |
Keywords: | Pichia pastoris pH sorbitol gene expression AOX human growth hormone |
|
|