Microorganism Immobilization via Surface-Displayed Adhesin
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Solution Overview
Problem
Current methods for immobilizing microbial cells are inefficient due to limitations such as restricted substance transportation speed, cell leakage, fragility of gel matrices, inhibition by crosslinking agents, and insufficient adhesiveness, particularly for general microbial cells, which hinders their industrial application.
Innovation Solution
A method involving the introduction of the ataA gene, encoding the trimeric autotransporter adhesin AtaA, to impart non-specific adhesiveness to microorganisms, allowing for high immobilization efficiency by attaching and releasing them based on ionic strength, enabling repeated use without catalyst function degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If gel matrix entrapment is used for immobilization, then the biocatalyst can be reused, but the substance transportation speed is restricted and the gel is fragile
Solution Approach 1:
The patent extracts the microbial cells from the gel matrix environment and immobilizes them directly on solid carriers using surface display technology. The enzyme is displayed on the cell surface, allowing direct contact with substrates in the reaction medium without diffusion through gel pores, thereby eliminating the substance transportation restriction while maintaining reusability through immobilization.
Solution Approach 2:
The patent uses solid carriers with porous structures that allow free diffusion of substrates and products. The pores in these carriers are large enough to accommodate microbial cells and allow unrestricted substance transportation, unlike the dense gel matrix structures that restrict diffusion.
2Stability of the object's composition
If crosslinking or covalent bonding is used for immobilization, then the biocatalyst can be stabilized, but the crosslinking agent inhibits reaction and the cells are inactivated
Solution Approach 1:
The patent uses the microbial cell surface itself as an intermediary for immobilization. The enzyme is displayed on the cell surface, and the cell wall/membrane acts as a natural intermediary that binds to the solid carrier without requiring external crosslinking agents. This eliminates the harmful effects of crosslinking agents while maintaining stability through the natural cell structure and surface display.
Solution Approach 2:
The microbial cells possess natural adhesiveness and surface structures that enable them to attach to solid carriers without external assistance. The surface-displayed enzyme is naturally anchored to the cell surface, eliminating the need for covalent bonding or crosslinking agents that would otherwise be required to stabilize the biocatalyst.
3Ease of manufacture
If physical adsorption is used for immobilization, then the process is simple, but the adhesiveness is insufficient for general microbial cells
Solution Approach 1:
The patent concentrates adhesiveness at the local level by displaying the enzyme and adhesion structures on the microbial cell surface. This creates localized regions of high adhesiveness at the cell surface that enable strong binding to solid carriers, while the rest of the cell maintains its natural properties. The surface display technology ensures that adhesion functions are concentrated where needed for immobilization.
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
This method provides a versatile and effective immobilization technique with high adhesiveness and repeated use capability, overcoming previous limitations and maintaining catalyst function, thus enhancing bioprocess efficiency and cost-effectiveness.
Implementation Method 1
contacting a microorganism, into which DNA encoding autotransporter adhesin derived from a microorganism belonging to the genus Acinetobacter has been introduced to impart or enhance non-specific adhesiveness, with a carrier under a high ionic strength and thus attaching the microorganism to the carrier
Implementation Method 2
releasing the microorganism from the carrier by washing under a low ionic strength
Data Source
Figure 1A~1B
Figure 2A~2D
Figure 3
AI summary
Intended is to provide a more practical technique for immobilizing a microorganism using an adhesive protein AtaA derived from Acinetobacter sp. Tol 5. Provided is a method for attaching and releasing a microorganism, including (1) a step of contacting a microorganism, into which DNA encoding autotransporter adhesin derived from a microorganism belonging to the genus Acinetobacter has been introduced to impart or enhance non-specific adhesiveness, with a carrier under a high ionic strength and thus attaching the microorganism to the carrier; and (2) a step of releasing the microorganism from the carrier by washing under a low ionic strength.