Yeast MIG3 Overexpression Reduces Acetate in Ethanol Fermentation
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Solution Overview
Problem
Engineered yeast strains that incorporate a heterologous phosphoketolase pathway produce increased acetate during ethanol production, which is undesirable as it affects yeast growth and fermentation, and requires pH adjustments or increased water usage in subsequent fermentation batches.
Innovation Solution
Modified yeast cells that over-express MIG transcription regulator polypeptides, reducing acetate production by increasing MIG transcription regulator mRNA levels up to 100-fold compared to parental cells, thereby decreasing acetate production by up to 60%.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a heterologous phosphoketolase pathway is introduced into yeast to increase ethanol production, then ethanol production is improved, but acetate production increases which is harmful to yeast growth and fermentation
Solution Approach 1:
The patent introduces MIG transcription regulators as intermediary molecules that mediate between the phosphoketolase pathway and acetate production. These regulators bind to specific DNA sequences to control the expression of enzymes involved in acetate formation, thereby reducing harmful acetate production while maintaining the beneficial phosphoketolase pathway for ethanol production
Solution Approach 2:
The patent modifies the transcriptional parameters of the yeast genome by introducing and overexpressing MIG transcription regulator genes. This changes the regulatory parameters of gene expression to suppress acetate-producing enzymes while allowing phosphoketolase pathway enzymes to function, thus resolving the contradiction between ethanol and acetate production
2Reliability
If acetate production is reduced by modifying yeast strains, then yeast growth and fermentation are improved, but the complexity of the yeast strain increases
Solution Approach 1:
The patent extracts and isolates the specific function of acetate production regulation from the complex yeast genome. By identifying and targeting only the specific transcription regulator genes (MIG1, MIG2, MIG3) that control acetate production, the patent simplifies the modification process compared to attempting to redesign the entire yeast metabolism, thus improving reliability while limiting complexity increase
Data Source
AI summary
Described are compositions and methods relating to modified yeast that over-express MIG transcriptional regulator polypeptides. The yeast produces a deceased amount of acetate compared to parental cells. Such yeast is particularly useful for large-scale ethanol production from starch substrates where acetate in an undesirable end product.