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Characterization of a nutrient feed precipitate from an E. coli fermentation process.
Lauren Speciner1, Erin Mallon, Susan Leung
1Process Development Engineering, Genentech, Inc., 1 DNA Way, South San Francisco, CA 94080, USA.
Biotechnology Progress
|October 15, 2010
Summary
Insoluble zinc precipitate formed during microbial fermentation nutrient preparation. Inorganic phosphate in glycerophosphate caused zinc precipitation, impacting product yield.
Area of Science:
- Biochemistry
- Chemical Engineering
- Manufacturing Processes
Background:
- Metalloproteins require soluble zinc for proper folding, stability, and biological activity.
- Nutrient supplements provide essential metals like zinc during microbial fermentation for protein production.
- Manufacturing-scale recombinant protein production necessitates careful control of nutrient feed composition.
Purpose of the Study:
- To investigate the cause of an insoluble precipitate formed in a manufacturing-scale nutrient feed (methionine, glycerophosphate, and zinc sulfate - MGZ).
- To identify the components responsible for zinc precipitation in the nutrient feed.
- To understand the impact of this precipitation on zinc availability for recombinant protein production.
Main Methods:
- Analysis of the precipitate using capillary zone electrophoresis.
- Quantification of precipitate components using inductively coupled plasma (ICP) analysis.
- Assay of inorganic phosphate using the phosphate molybdate method.
Main Results:
- The precipitate was identified as a zinc-phosphate compound.
- Inorganic phosphate, present as an impurity in the glycerophosphate component of the MGZ feed, was found to be the cause of zinc precipitation.
- Steam sterilization of the nutrient feed exacerbated the precipitation process.
Conclusions:
- The presence of inorganic phosphate in the glycerophosphate nutrient supplement leads to zinc precipitation.
- This zinc precipitation reduces the soluble zinc available for metalloprotein production during fermentation.
- Optimizing the purity of glycerophosphate or implementing alternative zinc delivery methods is crucial for successful manufacturing-scale protein production.
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