Bt Research 2025, Vol.16, No.4, 125-135 http://microbescipublisher.com/index.php/bt 132 copy number of each bacterial cell can be flexibly adjusted between 1 and 800, which provides an effective means to balance bacterial metabolic stress and maximize toxin production (Rouches et al., 2021). This fine regulatory ability is of great significance for improving the performance and stability of engineered Bt strains in different environments. 7.2 Develop an environment-responsive expression system to control toxin release Another promising direction is to create a "system that can adjust its expression in response to the environment", allowing Bt toxins to be regulated and activated for release only when needed. Researchers can add some regulatory components that are sensitive to environmental signals to the plasmid, such as those sensitive to light, temperature or specific chemicals. This way, "temporal and spatial control" of the expression of toxin genes can be achieved. For instance, light-controlled plasmids have been developed: they feature a modified promoter that can be cut off by light, enabling remote activation of gene expression without direct manipulation of bacteria (Chung and Booth, 2023). This method not only reduces the impact on non-target organisms but also only produces toxins when necessary, thereby enhancing overall biological safety. This response system can also be designed to "sense the presence of pests" or "sense the signals of plant stress" - only activating the expression of insecticidal genes when necessary. This strategy can reduce the unnecessary metabolic burden on host bacteria, lower the exposure to Bt toxins in the environment, address key biosafety and ecological issues, and at the same time maintain efficient pest control effects. 7.3 Integrate multi-omics and genome editing to construct broad-spectrum and highly efficient Bt strains Combining "multi-omics methods" (such as genomics, transcriptomics, and proteomics) with advanced genome editing technologies offers new opportunities for constructing Bt strains with "stronger insecticidal activity and the ability to target more pests". Multi-omics analysis can comprehensively reveal gene functions, regulatory networks and metabolic pathways, providing guidance for the rational design of plasmids and the selection of the optimal combination of toxin genes. This system-level understanding can help researchers identify new renovation targets and predict possible unexpected impacts. Genome editing tools (including CRISPR/Cas systems) can precisely modify plasmid and chromosomal DNA to achieve the insertion, deletion or replacement of toxin genes and regulatory elements. These techniques have been successfully used to design "plasmids that can be used in multiple hosts" and to knock out or inhibit specific genes-fully demonstrating their role in fine-tuning the performance of Bt strains (Leonard et al., 2018). Combining multi-omics data with genome editing will accelerate the development of "the next generation of efficient and environmentally friendly" Bt strains. 8 Concluding Remarks Engineering Bt plasmids have become an important foundation for promoting biological pest control. They can help cultivate strains and crops with stronger insecticidal effects, control more types of pests, and better deal with new problems constantly emerging in agriculture. With the help of DNA recombination technology, people can efficiently introduce and express new insecticidal protein genes, thereby developing Bt pesticides and genetically modified crops with more comprehensive functions and better effects. This not only reduces the reliance on chemical pesticides but also provides support for the sustainable development of agriculture. In order to smoothly design and promote the use of enhanced Bt plasmids, close cooperation among fields such as molecular biology, ecology, agronomy and regulatory science is required. Innovative approaches such as protein engineering, advanced transformation methods, and systematic biosafety assessment have all played a significant role in addressing technical challenges, reducing ecological risks, and controlling pest resistance. Multidisciplinary collaboration will promote the development of the new generation of Bt technology, ensuring that it functions efficiently while also protecting the environment. With the continuous advancement of genetic engineering, protein modification and integrated pest management technologies, transgenic Bt strains and crops will play a greater role in sustainable pest control. They only act on
RkJQdWJsaXNoZXIy MjQ4ODYzNA==