Microbial Hosts Engineered for Temperature Shift Tolerance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Mesophilic microorganisms lack robustness at varying temperatures, limiting their industrial applications due to genetic inaccessibility and high costs associated with using thermophiles, which are genetically inaccessible and expensive to culture at high temperatures.
Innovation Solution
Engineering microbial host cells by replacing endogenous NAD+ biosynthesis genes with heterologous enzymes from thermophilic or psychrophilic organisms, enhancing temperature tolerance and performance across different temperature ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If thermophiles are used for high temperature fermentation, then temperature robustness and productivity are improved, but genetic accessibility and cultural cost increase
Solution Approach 1:
The patent extracts and replaces specific endogenous NAD+ biosynthesis genes (nadB and/or nadA) with heterologous genes from thermophilic or psychrophilic organisms. This selective gene replacement approach allows mesophilic hosts to acquire temperature tolerance traits without the complexity of whole-organism thermophilic engineering, thereby improving temperature robustness while maintaining genetic accessibility.
Solution Approach 2:
The patent uses heterologous NAD+ biosynthesis enzymes from thermophilic or psychrophilic organisms as intermediaries to confer temperature tolerance on mesophilic host cells. These heterologous enzymes act as mediators that enable the host to function robustly across extended temperature ranges without requiring the host to be a native thermophile, thus resolving the contradiction between temperature robustness and genetic accessibility.
2Productivity
If thermophiles are used for high temperature fermentation, then productivity and enzyme stability are improved, but cultural cost increases
Solution Approach 1:
The patent copies and transfers specific functional genes (nadB and/or nadA) from thermophilic or psychrophilic organisms into mesophilic host cells. This gene copying approach allows the host to adopt temperature tolerance characteristics and improved productivity traits from thermophiles while avoiding the high cultural costs associated with maintaining pure thermophilic cultures, as the mesophilic host can be cultured under standard conditions.
3Reliability
If endogenous NAD+ biosynthesis genes are replaced with heterologous genes, then temperature tolerance is improved, but genetic complexity increases
Solution Approach 1:
The patent extracts and replaces specific endogenous NAD+ biosynthesis genes (nadB and/or nadA) with heterologous genes. By targeting only these specific genes rather than performing genome-wide engineering, the patent achieves temperature tolerance improvement while minimizing the increase in genetic modification complexity. The replaced genes are typically single-copy and well-defined, making the engineering process manageable.
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 microbial host cells exhibit improved temperature tolerance and performance, reducing the lag phase and increasing growth rates, thereby enhancing industrial applications and reducing cultural costs.
Implementation Method 1
de novo biosynthesis of NAD+ proceeds via a condensation reaction of L-aspartate and dihydroxyacetone phosphate, catalysed by the quinolinate synthase system
Implementation Method 2
L-aspartate oxidase (NadB) which catalyses the oxidation of L-aspartate to iminoaspartate using O2 as an electron receptor, releasing H2O2
Data Source
AI summary
The present invention relates to microbial host cells that have been engineered for increased tolerance to temperature shifts, for increased performance at temperatures different from the microorganism's optimal temperature and/or for changing at least one of the microorganism's cardinal temperatures by replacing an endogenous NAD+ biosynthesis gene by a heterologous gene encoding a corresponding enzyme with another temperature profile and/or from a microorganism with a different optimum growth temperature. The invention further relates to processes wherein the engineered microbial host cells are used for producing a fermentation product, and to the use nucleotide sequences encoding NAD+ biosynthesis gene for changing at least one of a microorganism's cardinal temperatures and/or for improving a microorganism's tolerance to temperature shifts.