Bt Research 2025, Vol.16, No.2, 70-78 http://microbescipublisher.com/index.php/bt 70 Research Report Open Access Genetic Diversity and Population Structure of Bacillus thuringiensis in Different Ecosystems Xiaoyun Wang, Jun Li Animal Science Research Center, Cuixi Academy of Biotechnology, Zhuji, 311800, Zhejiang, China Corresponding author: jun.li@cuixi.org Bt Research, 2025, Vol.16, No.2 doi: 10.5376/bt.2025.16.0009 Received: 10 Feb., 2025 Accepted: 25 Mar., 2025 Published: 12 Apr., 2025 Copyright © 2025 Wang and Li, This is an open access article published under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Preferred citation for this article: Wang X.Y., and Li J., 2025, Genetic diversity and population structure of Bacillus thuringiensis in different ecosystems, Bt Research, 16(2): 70-78 (doi: 10.5376/bt.2025.16.0009) Abstract This study summarizes the genetic diversity and population structure of Bt in different ecosystems, analyzes the genotype distribution of Bt populations in soil, plant, insect-related and aquatic environments, the diversity of toxin genes, and the relationship between these genes and ecological functions, and explores how climate change, host diversity and agricultural activities promote the genetic differentiation of Bt. It also emphasized the great potential and current research deficiencies of metagenomics and multi-omics technologies in studying the dynamics of Bt populations, horizontal gene transfer and ecological adaptability. This study aims to provide a theoretical basis and future research direction for understanding the ecological functions of Bt and its sustainable utilization in biological control. Keywords Bacillus thuringiensis; Genetic diversity; Population structure; Metagenomics; Biocontrol applications 1 Introduction Bacillus thuringiensis (Bt) is a Gram-positive spore-forming bacterium that is widely present in environments such as soil, plants and water bodies. It can produce δ -endotoxins, such as Cry and Cyt proteins, which have strong specificity and insecticidal ability against various insects (Yu and Zhou, 2024). Bt is currently the most widely used biological insecticide worldwide and also the main source of insect-resistant genes in genetically modified crops. It has played a significant role in the green control of agricultural pests and disease vectors. Furthermore, Bt can also produce some antibacterial, antifungal and growth-promoting substances, which help maintain the microbial diversity and function of the ecosystem (Mishra et al., 2017; Yilmaz et al., 2024). The genetic diversity and population structure of microorganisms are the basis for understanding their ecological adaptability, evolutionary potential and functional differentiation. Research has found that Bt has a high genetic diversity in different geographical regions, ecological environments and hosts. This diversity is not only reflected in toxin genes, but also involves changes in genomic structure, plasmid composition and functional genes (Navya et al., 2021; Berçot et al., 2023; Pheepakpraw et al., 2023). Studies on population structure have shown that there are dynamic processes such as gene flow, recombination and clonal amplification in Bt populations, which can affect the distribution of Bt in the natural environment, niche occupation and persistence as a biological control factor (Vilas-Bôas et al., 2002; Hu et al., 2020). Furthermore, the gene exchange between Bt and its related species such as Bacillus cereus can also affect its ecological adaptation and related risk assessment. This study utilized molecular markers and genomic sequencing to assess the genetic diversity of Bt in different ecosystems, analyzed the population structure of Bt populations, as well as their relationships with ecological environment, geographical distribution, and functional genotypes. It also explored the impacts of genetic mechanisms such as gene flow, recombination, and plasmid transfer on the diversity and population structure of Bt. This study aims to provide a theoretical basis for understanding the ecological functions and biological control applications of Bt. 2 Methods for Assessing Genetic Diversity in Bt 2.1 Molecular markers and genotyping techniques When evaluating the genetic diversity of Bt, commonly used molecular marker methods include RAPD (randomly
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