Bacterial Yeast Consortium Reducing CO2 in Ethanol Fermentation
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Solution Overview
Problem
Current ethanol production from biomass using Saccharomyces cerevisiae results in significant CO2 emissions due to the conversion of glucose into ethanol and carbon dioxide, necessitating a reduction in greenhouse gas production while maintaining ethanol yield.
Innovation Solution
A combination of a bacterial host cell and a yeast host cell is used, where the bacterial host cell converts acetate and glycerol into ethanol, reducing CO2 production, and the yeast host cell generates acetate and glycerol, optimizing the metabolic pathways to enhance ethanol production while minimizing CO2 emissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If yeast host cell converts hexoses into ethanol through glycolysis, then ethanol production is achieved, but CO2 emissions increase significantly
Solution Approach 1:
The patent converts the harmful CO2 emissions into useful ethanol product by introducing a bacterial host cell that can metabolize acetate (a byproduct of yeast fermentation) into ethanol through a complete TCA cycle pathway. The bacterial cell expresses heterologous enzymes including citrate synthase, aconitase, isocitrate dehydrogenase, alpha-ketoglutarate dehydrogenase, succinyl-CoA synthetase, succinate dehydrogenase, fumarase, and malate dehydrogenase to complete the TCA cycle and produce ethanol from acetate, thereby converting the harmful CO2 byproduct into beneficial ethanol fuel.
Solution Approach 2:
The patent merges two different host cells (yeast and bacteria) into a hybrid fermentation system where the yeast performs initial hexose fermentation and the bacterial component completes the conversion of acetate to ethanol. This combined system integrates the metabolic pathways of both organisms to achieve complete carbon conversion and minimize CO2 emissions while maximizing ethanol yield.
2Object-generated harmful factors
If bacterial host cell converts acetate into ethanol through TCA cycle, then CO2 emissions are reduced, but metabolic pathway complexity increases
Solution Approach 1:
The patent uses the bacterial host cell as an intermediary organism that bridges the metabolic gap between yeast fermentation and complete ethanol production. The bacterial cell introduces heterologous enzymes as intermediary catalysts to facilitate the TCA cycle reactions that convert acetate into ethanol, thereby mediating the transformation of yeast byproducts into additional ethanol while managing the metabolic complexity through specialized bacterial machinery.
3Productivity
If yeast host cell produces glycerol and acetate as byproducts, then ethanol fermentation proceeds, but greenhouse gas accumulation increases
Solution Approach 1:
The patent recovers and utilizes the previously discarded byproducts (acetate and glycerol) of yeast fermentation. Instead of allowing these substances to accumulate as waste or greenhouse gas precursors, the bacterial host cell metabolizes acetate through the TCA cycle to produce additional ethanol, thereby recovering valuable carbon that would otherwise be lost or converted to CO2, and improving overall fermentation efficiency.
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 reduces CO2 emissions during ethanol production from biomass, maintaining or increasing ethanol yield compared to conventional yeast fermentation, by efficiently utilizing glycerol and acetate to produce ethanol without generating additional CO2.
Implementation Method 1
a first metabolic pathway comprising one or more first polypeptides for converting acetate into ethanol
Implementation Method 2
a second metabolic pathway comprising one or more second polypeptides for the conversion of glycerol into dihydroxyacetone phosphate
Implementation Method 3
a fourth metabolic pathway comprising one or more fourth polypeptides for producing glycerol
Implementation Method 4
a fifth metabolic pathway comprising one or more fifth polypeptides for generating acetate
Data Source
AI summary
The present disclosure concerns a symbiotic combination of a bacterial host cell and a yeast host cell selected or engineered to utilize glycerol to reduce greenhouse gases during the production of ethanol from a biomass comprising hexoses.