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Evaluation of Metals in a Defined Medium for Pichia pastoris Expressing Recombinant β‐Galactosidase
Author(s) -
Plantz Bradley A.,
Nickerson Kenneth,
Kachman Stephen D.,
Schlegel Vicki L.
Publication year - 2008
Publication title -
biotechnology progress
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.572
H-Index - 129
eISSN - 1520-6033
pISSN - 8756-7938
DOI - 10.1021/bp060332t
Subject(s) - pichia pastoris , zinc , recombinant dna , chemistry , yield (engineering) , manganese , magnesium , metal , fermentation , biochemistry , chromatography , food science , metallurgy , materials science , organic chemistry , gene
Culture growth and recombinant protein yield of the Pichia pastoris GS115 methanol utilization positive system were studied in response to the types and levels of metals present in the growth medium and the supplemental salts typically used for these fermentations. Magnesium and zinc were both required to support cell growth but at significantly reduced levels compared to the control. However, supplementation with calcium, cobalt, iron, manganese, iodine, boron, and molybdenum were not required to sustain cell mass. When the medium was reformulated with only zinc and magnesium, the cells grew to 12–15 generations, which are expected for high cell density fed‐batch fermentations. Product yields of the recombinant protein β‐galactosidase were significantly influenced by the trace metal concentrations. By using response surface and full factorial designs, maximum protein yield occurred when the concentration of zinc salt was limited to the level necessary only to support cell mass while protein yield positively correlated to increasing levels of the remaining trace metal salts. These studies are the first to show that excess trace metals must be optimized when developing P. pastoris based fed‐batch fermentations.