L-Cysteine Production via d0191 Gene Disruption
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Solution Overview
Problem
Current methods for enhancing L-cysteine production in bacteria are limited by the lack of effective techniques to modify bacterial strains for increased L-cysteine yield and stability, particularly involving the d0191 gene's cysteine desulfhydrase activity.
Innovation Solution
A bacterium belonging to the Enterobacteriaceae family, such as Pantoea ananatis, is modified to decrease the activity of the cysteine desulfhydrase protein encoded by the d0191 gene, either by reducing its expression or disrupting the gene, thereby enhancing L-cysteine production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the activity of cysteine desulfhydrase protein is decreased by modifying the d0191 gene, then L-cysteine production is enhanced, but the bacterial strain requires genetic modification which increases device complexity
Solution Approach 1:
The invention extracts and removes the harmful function of the d0191 gene by disrupting it through genetic modification. This eliminates the cysteine desulfhydrase activity that degrades L-cysteine, thereby enhancing L-cysteine production while managing the complexity through targeted gene disruption rather than complete pathway redesign
Solution Approach 2:
The invention changes the activity parameter of the cysteine desulfhydrase protein by modifying the d0191 gene expression levels or enzymatic activity. This parameter change directly increases L-cysteine stability and production without requiring complete pathway reconstruction, balancing productivity improvement with manageable genetic modification complexity
2Quantity of substance
If the d0191 gene activity is reduced to enhance L-cysteine accumulation, then the concentration of L-cysteine increases, but the loss of substance occurs through the original decomposition pathway
Solution Approach 1:
The invention converts the harmful decomposition function of cysteine desulfhydrase into a benefit by disrupting the d0191 gene. This eliminates the substance loss pathway, allowing L-cysteine to accumulate. The same genetic modification that removes the harmful degradation function simultaneously creates the beneficial accumulation effect
Solution Approach 2:
The invention applies preliminary anti-action by disrupting the d0191 gene before L-cysteine decomposition can occur. This preventive measure blocks the decomposition pathway in advance, ensuring that L-cysteine produced by the bacteria is not degraded, thereby maintaining high L-cysteine concentrations throughout the culture process
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 modification results in improved L-cysteine production, allowing for the accumulation of L-cysteine and its derivatives in the medium, with increased efficiency and resistance to cysteine inhibition.
Implementation Method 1
a novel gene encoding a protein having cysteine desulfhydrase activity has been found
Data Source
AI summary
The present invention describes a bacterium belonging to the family Enterobacteriaceae which has L-cysteine-producing ability and has been modified to decrease the activity of a protein encoded by the d0191 gene. This bacterium is cultured in a medium, and L-cysteine, L-cystine, derivatives thereof, or a mixture thereof is collected from the medium.