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Influence of pH on recombinant human growth hormone production by Pichia pastoris
Author(s) -
Çalık Pınar,
Bayraktar Eda,
İnankur Bahar,
Soyaslan Elif Ş.,
Şahin Merve,
Taşpınar Hatice,
Açık Eda,
Yılmaz Remziye,
Özdamar Tunçer H.
Publication year - 2010
Publication title -
journal of chemical technology and biotechnology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.64
H-Index - 117
eISSN - 1097-4660
pISSN - 0268-2575
DOI - 10.1002/jctb.2474
Subject(s) - pichia pastoris , chemistry , fermentation , human growth hormone , recombinant dna , protease , stimulation , growth hormone , enzyme , biochemistry , hormone , endocrinology , gene , biology
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. K L a 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 × 10 10 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 × 10 10 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