Genetically Modified Yeast Fermentation for Lactate From Sucrose
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Solution Overview
Problem
Many organisms are incapable of metabolizing sucrose and/or the fructose component, limiting their ability to produce lactate efficiently in fermentation processes.
Innovation Solution
Genetically engineered yeast cells with specific genetic modifications, including a deletion of the pyruvate decarboxylase gene, expression of exogenous lactate dehydrogenase and invertase enzymes, and introduction of a fructose transporter, enhance lactate production from sucrose.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If genetically engineered yeast cells are used to metabolize sucrose and fructose for lactate production, then lactate production efficiency is improved, but organism capability to metabolize fructose is limited
Solution Approach 1:
The patent introduces a fructose transporter gene (SUC2) to change the physiological parameter of fructose uptake capability in the yeast cell. This genetic modification enables the organism to transport and metabolize fructose effectively, resolving the limitation in fructose metabolism while maintaining high lactate production efficiency
Solution Approach 2:
The patent uses an exogenous invertase enzyme as an intermediary to break down sucrose into glucose and fructose. This intermediary enzyme enables the yeast to access and metabolize the fructose component of sucrose, which would otherwise be inaccessible to organisms lacking native sucrose metabolism capabilities
2Productivity
If pyruvate decarboxylase gene is deleted to redirect metabolism toward lactate, then lactate yield is improved, but metabolic flexibility is reduced
Solution Approach 1:
The patent extracts or removes the pyruvate decarboxylase gene (PDC1) from the yeast genome to eliminate the competing ethanol fermentation pathway. This extraction of the unwanted metabolic route redirects all pyruvate flux toward lactate production via lactate dehydrogenase, achieving high lactate yield while the introduced fructose transporter compensates for the reduced metabolic flexibility
3Adaptability or versatility
If exogenous enzymes are introduced to enable sucrose metabolism, then substrate utilization is improved, but genetic complexity increases
Solution Approach 1:
The patent employs the SUC2 gene, which encodes a fructose transporter that serves multiple functions: it enables fructose uptake from extracellular environment, supports fructose metabolism in the glycolytic pathway, and works synergistically with the introduced invertase enzyme. This multi-functional genetic element improves substrate utilization without proportionally increasing genetic complexity
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 engineered yeast cells demonstrate improved lactate production rates and titers, with peak production rates and volumetric oxygen uptake rates optimized for efficient lactate fermentation.
Implementation Method 1
a polynucleotide encoding an exogenous lactate dehydrogenase enzyme
Implementation Method 2
a polynucleotide encoding an exogenous invertase enzyme
Implementation Method 3
an exogenous polynucleotide encoding a fructose transporter
Implementation Method 4
Fermentation processes are used commercially at large scale to produce organic molecules such as ethanol, citric acid, and lactic acid
Data Source
AI summary
Disclosed herein are genetically engineered yeast cells capable of producing lactate from sucrose. The genetically engineered yeast cells comprise a polynucleotide encoding an exogenous lactate dehydrogenase enzyme; a polynucleotide encoding an exogenous invertase enzyme; a deletion or disruption of a native pyruvate decarboxylase (PDC) gene; and a genetic modification resulting in overexpression of a native hexokinase gene.