# Design microorganisms with precise target recognition capabilities for environmental or medical applications ## Key technology platform for gene editing 1. **CRISPR-Cas system** -Programmable DNA recognition system that can identify specific sequences to microorganisms -Use sgRNA design to achieve accurate identification of specific pollutants or pathogens -Can be combined with dCas9 (inactivated Cas9) to achieve binding instead of cutting function 2. **Synthetic biology tools** -Design of biosensor components (such as the use of transcription factors and ribose switches) -Engineering transformation of metabolic pathways -Modular gene circuit construction ## How to design an accurate identification system ### 1. Receptor system design -**Specific receptor protein**: Design membrane receptors that can bind to target pollutants -**Antibody fusion system**: Fusion of antibody variable regions with microbial surface proteins -**Aptamer technology**: Integrate nucleic acid or peptide aptamers that can recognize specific molecules ### 2. Signal conduction and execution mechanism -Construct a two-component system to transform recognition signals into gene expression regulation -Design positive/negative feedback loops to enhance system sensitivity and specificity -Integrate and gate logic circuits to ensure multiple confirmations and reduce the risk of false activation ## Practical application case design ### For environmental pollutants 1. Design a sensing system that can identify aromatic hydrocarbon pollutants 2. Activate the expression of degrading enzymes after recognition 3. Add a negative feedback mechanism to reduce enzyme expression after pollutant concentration decreases ### Target pathogens 1. Design a receptor system that recognizes molecules on the surface of a specific pathogen 2. Activate the secretion of antibacterial peptides or lysozymes after successful identification 3. At the same time activate the self-restriction system to prevent excessive microbial reproduction ##Safety and ethical considerations 1. **Biosafety design** -Integrate suicide genes to prevent microorganisms from leaking into the environment -Design a nutrient-dependent mechanism to limit the growth range -Add genetic barriers, such as unnatural amino acid dependence 2. **Regulatory and ethical issues** - Establish a rigorous laboratory and field testing program - Assess potential ecological impacts and gene level transfer risks -Comply with biosafety regulations and ethical review requirements This technical route requires interdisciplinary cooperation, including close cooperation in the fields of molecular biology, bioinformatics, biochemistry and environmental science.