Proteolytic Bacterial Hosts Supplying Yeast Nitrogen for Ethanol Fermentation
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Solution Overview
Problem
The bio-ethanol industry faces challenges with stuck or sluggish fermentations due to limited nitrogen availability for yeast, particularly when using urea as a nitrogen source, which imposes a metabolic burden and decreases growth rates, and the majority of amino nitrogen from proteins remains inaccessible.
Innovation Solution
A recombinant bacterial host cell with genetic modifications to enhance proteolytic activity, providing a nitrogen source through peptides, amino acids, and ammonia, thereby improving nitrogen availability for yeast fermentation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If urea is added to corn mash to increase fermentation performance, then nitrogen availability is improved, but metabolic burden increases and growth rates decrease
Solution Approach 1:
The invention changes the chemical form of nitrogen from urea (which requires cleavage into ammonia and CO2) to free amino acids and peptides (which are directly assimilable). This parameter change in nitrogen source chemistry eliminates the metabolic burden of urea cleavage while maintaining nitrogen availability for yeast fermentation.
Solution Approach 2:
The invention extracts and utilizes the nitrogen-containing compounds (free amino acids and peptides) directly from the corn mashing process itself, rather than adding external nitrogen sources like urea. This extraction approach provides nitrogen in a form that yeast can immediately use without additional metabolic processing.
2Quantity of substance
If exogenous protease is added to increase free amino acid availability, then fermentation performance improves, but process complexity and cost increase
Solution Approach 1:
The invention employs yeast's own endogenous proteolytic systems to break down proteins and release free amino acids during fermentation. This self-service approach eliminates the need for external protease additions while maintaining free amino acid availability, as the yeast naturally produces the necessary proteolytic activity during the fermentation process.
3Use of energy by moving object
If preferred nitrogen sources are provided to induce NCR, then metabolic efficiency improves, but nitrogen source options are limited
Solution Approach 1:
The invention provides a universal nitrogen source solution that works across different fermentation conditions and yeast strains. By utilizing free amino acids and peptides from corn mashing that trigger NCR, the system achieves both metabolic efficiency and broad adaptability, as this approach is compatible with standard industrial fermentation processes and various yeast varieties without requiring specialized nitrogen sources.
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
The recombinant bacterial host cell enhances fermentation yield and yeast robustness by increasing nitrogen availability, reducing the need for exogenous enzymes and urea, and maintaining the nutritional value of fermentation byproducts.
Implementation Method 1
The at least one first genetic modification is for increasing, when compared to a corresponding control bacterial cell lacking the at least one first genetic modification, the proteolytic activity associated with the recombinant bacterial host cell
Data Source
AI summary
The present disclosure concerns a recombinant bacterial host cell capable of providing a nitrogen source to a yeast during fermentation to make ethanol. The recombinant bacterial host cell is capable of converting a biomass into ethanol. The recombinant bacterial host cell has at least one first genetic modification. The at least one genetic modifications confers to the recombinant bacterial host cell the ability to increase, when compared to a corresponding control bacterial cell lacking the at least one first genetic modification, the proteolytic activity associated with the recombinant bacterial host cell. The at least one genetic modification also confers the recombinant bacterial host cell the ability to provide a nitrogen source to a yeast capable of converting the biomass into ethanol, wherein the nitrogen source comprises a peptide, an amino acid and/or ammonia.