Recombinant Strain Knockouts for 2,3-Butanediol Production
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Solution Overview
Problem
The high cost of carbon sources for microbial 2,3-butanediol production hinders its industrial viability, necessitating the development of efficient strains and carbon sources that can maximize the utilization of affordable substrates like sugarcane molasses.
Innovation Solution
A recombinant strain with an inactivated lactate dehydrogenase and sucrose regulator is developed, which, when cultured in a medium containing molasses, exhibits enhanced production efficiency of 2,3-butanediol by optimizing sucrose utilization pathways.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If expensive carbon sources are used for microbial 2,3-butanediol production, then production efficiency is improved, but production cost increases
Solution Approach 1:
The patent applies parameter changes by modifying the genetic parameters of the microorganism through gene knockout technology. Specifically, it knocks out the ldhA gene (lactate dehydrogenase) and scrR gene (sucrose regulator) to change the metabolic parameters of the strain, enabling it to efficiently utilize sucrose and molasses for 2,3-butanediol production while avoiding lactate formation, thus achieving high productivity with low-cost carbon sources
Solution Approach 2:
The patent creates a recombinant strain (Klebsiella pneumoniae ΔldhAΔscrR) that copies and optimizes the metabolic pathway for 2,3-butanediol production. By knocking out specific genes, the strain copies the desirable metabolic characteristics of wild-type strains that efficiently utilize sucrose while eliminating the harmful side reactions that produce lactate, thereby achieving both high efficiency and cost-effectiveness
2Productivity
If sucrose utilization pathway is optimized, then 2,3-butanediol production efficiency is improved, but metabolic pathway complexity increases
Solution Approach 1:
The patent applies the extraction principle by removing specific genes (ldhA and scrR) from the metabolic pathway to simplify the system. By taking out the ldhA gene, the harmful lactate production pathway is eliminated. By taking out the scrR gene (a repressor), the sucrose utilization pathway is activated and simplified, allowing direct conversion of sucrose to 2,3-butanediol without regulatory complications, thus achieving high efficiency without excessive complexity
3Quantity of substance
If lactate dehydrogenase is inactivated, then 2,3-butanediol yield is improved, but byproduct formation changes
Solution Approach 1:
The patent applies the 'blessing in disguise' principle by converting a potential harm (loss of NADH from blocked lactate pathway) into a benefit. By knocking out ldhA, the NADH that would have been consumed for lactate production is now redirected to support 2,3-butanediol production through the acetoin pathway, thereby increasing 2,3-butanediol yield while eliminating harmful lactate byproduct formation
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 strain achieves superior 2,3-butanediol production and productivity, improving efficiency by 10% or more and productivity by 60% compared to wild-type strains, utilizing sugarcane molasses as a carbon source.
Implementation Method 1
A PTS-dependent transporter imports sucrose with phosphorylation by Ellscr
Implementation Method 2
SucB, sucrose-6-phosphate hydrolase
Implementation Method 3
the microbial production of 2,3-butanediol as a platform chemical has attracted great interests
Data Source
AI summary
The present invention relates to a recombinant strain for producing 2,3-butanediol, comprising (a) an inactivated lactate dehydrogenase and (b) an inactivated sucrose regulator. According to the present invention, it is possible to economically produce 2,3-butanediol using a cheap carbon source, and the efficiency and productivity of 2,3-butanediol is remarkable compared with a wild type.