title: Oxygen transfer as a tool for fine-tuning recombinant protein production by Pichia pastoris under glyceraldehyde-3-phosphate dehydrogenase promoter.
abstract: Effects of oxygen transfer on recombinant protein production by Pichia pastoris under glyceraldehyde-3-phosphate dehydrogenase promoter were investigated. Recombinant glucose isomerase was chosen as the model protein. Two groups of oxygen transfer strategies were applied, one of which was based on constant oxygen transfer rate where aeration rate was Q O/V = 3 and 10 vvm, and agitation rate was N = 900 min(-1); while the other one was based on constant dissolved oxygen concentrations, C DO = 5, 10, 15, 20 and 40 % in the fermentation broth, by using predetermined exponential glucose feeding with μ o = 0.15 h(-1). The highest cell concentration was obtained as 44 g L(-1) at t = 9 h of the glucose fed-batch phase at C DO = 20 % operation while the highest volumetric and specific enzyme activities were obtained as 4440 U L(-1) and 126 U g(-1) cell, respectively at C DO = 15 % operation. Investigation of specific enzyme activities revealed that keeping C DO at 15 % was more advantageous with an expense of relatively higher by-product formation and lower specific cell growth rate. For this strategy, the highest oxygen transfer coefficient and oxygen uptake rate were K L a = 0.045 s(-1) and OUR = 8.91 mmol m(-3) s(-1), respectively.
authors.affiliation: Industrial Biotechnology and Metabolic Engineering Laboratory, Department of Chemical Engineering, Middle East Technical University, 06800, Ankara, Turkey.
authors.forename: Hande
authors.initials: H
authors.lastname: Güneş
authors.affiliation: Industrial Biotechnology and Metabolic Engineering Laboratory, Department of Chemical Engineering, Middle East Technical University, 06800, Ankara, Turkey. pcalik@metu.edu.tr.
authors.forename: Pınar
authors.initials: P
authors.lastname: Çalık
mesh_terms: D002455:Cell Division; D000431:Ethanol / Q000378:metabolism; D005947:Glucose / Q000378:metabolism; D005987:Glyceraldehyde-3-Phosphate Dehydrogenases / Q000235:genetics*; D010100:Oxygen / Q000378:metabolism*; D010843:Pichia / Q000235:genetics*; D011401:Promoter Regions, Genetic; D011994:Recombinant Proteins / Q000096:biosynthesis; D012995:Solubility
chemical_list: D011994:Recombinant Proteins; D000431:Ethanol; D005987:Glyceraldehyde-3-Phosphate Dehydrogenases; D005947:Glucose; D010100:Oxygen
keywords: Bioprocess design; Fed-batch culture; Fermentation; GAP promoter; Oxygen transfer; Pichia pastoris