Yeast PAB1 Overexpression Reduces Acetate in Ethanol Fermentation

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Solution Overview

Problem

Engineered yeast strains that utilize the phosphoketolase pathway for ethanol production tend to produce excessive acetate, which negatively affects yeast growth, fermentation, and requires pH adjustments or increased water usage in backset reuse.

Innovation Solution

Modified yeast over-expressing the polyadenylate-binding protein (PAB1) to decrease acetate production, achieved through genetic manipulation and increased expression of the PAB1 polypeptide, potentially combined with other genetic modifications like the PKL pathway and glycerol biosynthesis attenuation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the phosphoketolase pathway is genetically engineered into yeast to increase ethanol production, then ethanol production volume is improved, but acetate production increases which negatively affects yeast growth and fermentation

Engineering Contradiction:

Improveethanol production volumeVSAvoidacetate production

Core Design Contradiction:

ProductivityVSObject-generated harmful factors

Solution Approach 1:

The patent extracts and removes the harmful acetate byproduct from the fermentation process by introducing engineered pathways that convert acetate into ethanol, effectively taking out the harmful substance and transforming it into a useful product

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent converts the harmful acetate byproduct into beneficial ethanol through engineered metabolic pathways, transforming a harmful factor into a useful product that increases overall ethanol yield while eliminating negative effects on yeast growth

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

2Productivity

If acetate is produced by yeast during fermentation, then ethanol production is maintained, but pH of backset decreases requiring additional pH adjustments or fresh water usage

Engineering Contradiction:

Improveethanol productionVSAvoidfresh water usage

Core Design Contradiction:

ProductivityVSLoss of substance

Solution Approach 1:

The patent converts acetate (which causes pH reduction) into ethanol, thereby eliminating the need for pH adjustment and reducing fresh water consumption in backset reuse while maintaining ethanol production

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Duration of action of moving object

If acetate accumulates in backset from fermentation, then fermentation process continues, but quality of backset deteriorates requiring disposal or treatment

Engineering Contradiction:

Improvefermentation durationVSAvoidbackset quality

Core Design Contradiction:

Duration of action of moving objectVSReliability

Solution Approach 1:

The patent converts accumulated acetate in backset into ethanol through engineered pathways, thereby maintaining backset quality and enabling reuse without disposal or treatment, extending the reliable operation of the fermentation process

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Data Source

PatentEP3762499B1Reduction in acetate production by yeast over-expressing PAB1

Publication Date: 2023.12.20 DANISCO US INC

AI summary

Described are compositions and methods relating to modified yeast that over-express polyadenylate-binding protein (PAB1). 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.