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African Journal of Biotechnology

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Comparison between constant methanol feed and on-line monitoring feed control for recombinant human growth hormone production by Pichia pastoris KM71

Yardrung Suwannarat, Sornpichai Saeseaw, Niwat Chanasutthiprapa, Anan Tongta

Abstract


Two methanol feeding methods, namely constant methanol feed and on-line monitoring feed control by methanol sensor were investigated to improve the production of recombinant human growth hormone (rhGH) in high cell density cultivation of Pichia pastoris KM71 in 2 L bioreactor. The yeast utilized glycerol as a carbon source for cell growth and yeast cells were accumulated to high cell density. Cell dry weight concentration around 140 to 150 g/l was obtained before entering the methanol induction period. Methanol was applied to express rhGH after high cell accumulation. The constant methanol feed rate at 0.009 l/h was applied to the cultivation to compare with the on-line monitoring feed control of methanol concentration. The highest amount of rhGH around 501 mg/l was obtained by using on-line monitoring feed control of methanol at the set point of methanol concentration at 4.0 g/l. After achieving the best result from the on-line monitoring feed control method, the experiment was further carried out to investigate the optimal methanol concentration. On-line controlling of methanol concentrations at 2.0, 4.0 and 8.0 g/l were investigated. The result shows that high amount of rhGH was achieved by controlling the methanol level at the set point of 4.0 g/l.

Key words: Recombinant human growth hormone, Pichia pastoris, fed-batch cultivation, methanol feeding control.




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