Unprecipitating Bacterial Fermentation Media for High-Density Cultures
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Solution Overview
Problem
Fed-batch high-density fermentations of E.coli suffer from moderate to heavy precipitation in the cell culture medium, which can affect nutrient availability, analytics, and downstream processing, and is undesirable due to variations in handling and upscaling.
Innovation Solution
A method using unprecipitating batch and feed media solutions for bacterial fermentation, where the batch medium contains calcium, magnesium, and phosphate salts along with a chelating agent like citrate or EDTA, and the feed medium has increased calcium and magnesium salts while reducing phosphate salts, preventing precipitation within the pH range of 6.7-7.3.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional batch and feed media are used in fed-batch high-density fermentation of E.coli, then high cell density can be achieved, but precipitation occurs in the cell culture medium affecting nutrient availability and downstream processing
Solution Approach 1:
The invention changes the chemical parameters of the medium by replacing traditional phosphate buffer with HEPES buffer (pH 6.7-7.3) and adjusting salt concentrations. This parameter change prevents precipitation while maintaining high cell density fermentation, directly resolving the contradiction between productivity and harmful precipitation effects
Solution Approach 2:
HEPES buffer acts as an intermediary substance that provides pH buffering capacity without causing precipitation. It mediates between the need for stable pH at high cell density and the avoidance of precipitate formation, allowing both high productivity and clear medium
2Ease of manufacture
If pH is adjusted to desired value around pH 7.0 or heat sterilization is performed, then medium is prepared for fermentation, but precipitation occurs during these preparation steps
Solution Approach 1:
The invention changes the pH parameter range to 6.7-7.3 and uses HEPES buffer which maintains solubility across this range. This allows medium preparation including pH adjustment and heat sterilization without precipitation, improving ease of manufacture while eliminating harmful precipitation
3Quantity of substance
If phosphate salts are present in conventional media, then nutrient availability is maintained, but co-precipitation with magnesium salts occurs reducing nutrient availability
Solution Approach 1:
HEPES buffer serves as an intermediary pH buffering system that replaces phosphate salts. This eliminates the harmful co-precipitation between phosphate and magnesium salts while maintaining nutrient availability through alternative buffering, resolving the contradiction between quantity of substance and object-generated harmful factors
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach effectively prevents precipitation in the bacterial fermentation process, improving the consistency and robustness of fermentations, especially under high cell density conditions, and maintains high titers of the fermentation product.
Implementation Method 1
The batch medium comprises an amount of calcium salts, magnesium salts, phosphate salts and at least one chelating agent, which is a citrate salt and/or citric acid at an amount of at least 5 mM, and/or EDTA at an amount of at least 1 mM
Data Source
AI summary
A method of reducing precipitation in a bacterial fermentation process for producing a fermentation product, which fermentation process comprises the steps:a) cultivating the host cells for bacterial growth in a batch phase using a batch medium; andb) cultivating the host cells for producing the fermentation product in a fed-batch phase using a feed medium;which feed and batch media are each unprecipitated media solutions, wherein:i) the batch medium comprises an amount of calcium salts, magnesium salts, phosphate salts and at least one chelating agent, which is a citrate salt and/or citric acid at an amount of at least 5 mM, and/or EDTA at an amount of at least 1 mM; andii) the feed medium comprises an amount of calcium salts which is at least 1 mM, and which is at least 5-fold higher as compared to the batch medium (M/M); andiii) the feed medium comprises an amount of magnesium salts which is at least 3 mM, and which is at least 2-fold higher as compared to the batch medium (M/M); andiv) the feed medium comprises an amount of phosphate salts which is less than 90% of the amount comprised in the batch medium (M/M).