Bacillus licheniformis Genetic Modification via Auxotrophic Selection
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Solution Overview
Problem
Current methods for genetically modifying Bacillus licheniformis host cells for enhanced protein production are limited by random mutagenesis and the use of antibiotic resistance markers, leading to undesirable mutations and antibiotic resistance issues.
Innovation Solution
The development of methods and compositions for creating auxotrophic Bacillus licheniformis cells by inactivating genes such as lysA, serA, and pyrF, and subsequently introducing recombinant DNA constructs with selectable markers to restore prototrophy and express proteins of interest.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If random mutagenesis is used for strain improvement, then protein production may increase, but undesirable mutations occur and reliability deteriorates
Solution Approach 1:
The patent applies preliminary action by first creating auxotrophic mutations in specific genes (lysA, serA, pyrF) before introducing the desired protein production capabilities. This pre-established genetic modification creates a controlled platform that directs subsequent genetic changes toward productive outcomes rather than random mutations, thereby improving reliability while maintaining productivity gains.
Solution Approach 2:
The patent employs parameter changes by shifting from random mutagenesis to targeted gene inactivation followed by controlled recombinant DNA introduction. This changes the fundamental parameter of genetic modification approach from stochastic to deterministic, ensuring that mutations lead to desired protein production without undesirable side effects, thus resolving the contradiction between productivity improvement and strain stability.
2Productivity
If antibiotic resistance markers are used for selection, then transformation efficiency improves, but antibiotic resistance issues arise
Solution Approach 1:
The patent applies the taking out principle by removing antibiotic resistance markers from the selection process entirely. Instead, it uses auxotrophic selection where the inactivation of essential genes (lysA, serA, pyrF) creates a selection system that does not require antibiotics. This extracts the harmful antibiotic resistance element while preserving the beneficial transformation efficiency through alternative selection mechanisms.
Solution Approach 2:
The patent introduces auxotrophic markers as an intermediary selection mechanism. Rather than directly using antibiotic resistance for selection, the system employs auxotrophic mutations as an intermediate step that enables selection through nutritional requirements. This intermediary approach achieves efficient transformation selection without generating antibiotic resistance, resolving the contradiction between productivity and harmful effects.
3Productivity
If multiple rounds of strain improvement are performed, then protein yield increases, but the process complexity increases and time is lost
Solution Approach 1:
The patent applies merging by combining multiple genetic modification objectives into a single integrated process. Instead of performing separate rounds of mutagenesis and selection, the auxotrophic platform allows simultaneous achievement of stable strain construction and protein production enhancement in one coordinated workflow. This merging reduces the number of iterative cycles needed, thereby decreasing time loss while maintaining high protein yield improvements.
Solution Approach 2:
The patent uses preliminary action by pre-establishing the auxotrophic genetic platform before undertaking protein production optimization. This preliminary construction creates a stable, selectable background that accelerates subsequent strain improvement efforts. By preparing this foundation in advance, the overall strain development time is reduced because subsequent modifications build on a ready-made platform rather than starting from scratch each round.
Data Source
AI summary
The instant disclosure is generally related to compositions and methods for obtaining and constructing Bacillus licheniformis host cells (e.g., protein production host cells, cell factories) having increased protein production capabilities. Certain embodiments of the disclosure are directed to efficient genetic modifications of B. licheniformis cells and the subsequent selection of such B. licheniformis cells having increased protein production capabilities. Certain other embodiments of the disclosure are generally related to methods and compositions for producing/obtaining auxotrophic B. licheniformis cells, wherein certain other embodiments of the disclosure are directed to methods and compositions for restoring prototrophy in auxotrophic B. licheniformis cells, and expressing genes of interest (GOIs) in such restored prototrophy B. licheniformis cells.