Continuous Fermentation with Membrane Filtration for Catabolite Repression
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Solution Overview
Problem
Continuous fermentation using a mixed sugar of hexose and pentose as a fermentation feedstock for microorganisms that undergo catabolite repression results in lower yields due to catabolite repression, which hampers the production of biodegradable polymer materials and biofuels.
Innovation Solution
A method involving continuous fermentation with a separation membrane to filter the culture liquid of microorganisms that undergo catabolite repression, adding a fermentation feedstock containing hexose and pentose, and recovering the product in the filtrate, maintaining a pentose concentration below 5 g/L and adjusting the hexose to pentose weight ratio between 1:9 to 9:1.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If continuous fermentation is performed using a mixed sugar of hexose and pentose as a fermentation feedstock for microorganisms that undergo catabolite repression, then productivity is improved through continuous operation, but fermentation yield deteriorates due to catabolite repression
Solution Approach 1:
The fermentation process is segmented into two distinct stages: a first continuous fermentation stage using hexose-containing feedstock, and a second continuous fermentation stage using pentose-containing feedstock. This segmentation allows each stage to operate under optimized conditions without the negative effects of catabolite repression, thereby maintaining both high productivity and high fermentation yield throughout the continuous operation.
2Ease of manufacture
If a microorganism that undergoes catabolite repression is used for continuous fermentation with mixed sugar, then ease of manufacture is improved by using known microorganisms, but fermentation yield deteriorates significantly
Solution Approach 1:
The fermentation process is segmented into two distinct stages: a first continuous fermentation stage using hexose-containing feedstock, and a second continuous fermentation stage using pentose-containing feedstock. This segmentation allows each stage to operate under optimized conditions without the negative effects of catabolite repression, thereby maintaining both high productivity and high fermentation yield throughout the continuous operation.
Solution Approach 2:
The system implements periodic switching between hexose feedstock and pentose feedstock in a cyclic manner. This periodic action allows the microorganism to alternate between metabolizing different sugar types, preventing continuous exposure to the catabolite repression condition while maintaining continuous production capability.
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 method enhances the yield of chemical products by mitigating the effects of catabolite repression, allowing for efficient production even with microorganisms that typically experience reduced fermentation efficiency when using mixed sugars.
Implementation Method 1
filtering a culture liquid of a microorganism(s) through a separation membrane
Data Source
AI summary
A method produces a chemical product by continuous fermentation including filtering a culture liquid of a microorganism(s) through a separation membrane, retaining unfiltered liquid in, or refluxing unfiltered liquid to, the culture liquid, adding a fermentation feedstock to the culture liquid, and recovering a product in the filtrate, wherein the microorganism(s) is/are a microorganism(s) that undergo(es) catabolite repression, and the fermentation feedstock comprises hexose and pentose.