Bt Research 2024, Vol.15, No.3, 154-163 http://microbescipublisher.com/index.php/bt 154 Feature Review Open Access Genomic Architecture of Bacillus thuringiensis: Insights into Functional Elements Jiamin Wang, Jin Zhang Hainan Key Laboratory of Crop Molecular Breeding, Sanya, 572025, Hainan, China Corresponding author: jin.zhang@hitar.org Bt Research, 2024, Vol.15, No.3 doi: 10.5376/bt.2024.15.0015 Received: 09 May., 2024 Accepted: 10 Jun., 2024 Published: 25 Jun., 2024 Copyright © 2024 Wang and Zhang, 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 J.M., and Zhang J., 2024, Genomic architecture of Bacillus thuringiensis: insights into functional elements, Bt Research, 15(3): 154-163 (doi: 10.5376/bt.2024.15.0015) Abstract Bacillus thuringiensis (Bt) is a Gram-positive bacterium renowned for its insecticidal properties, primarily due to the production of Cry and Cyt toxins. This systematic review delves into the genomic architecture of Bt, highlighting the functional elements that contribute to its efficacy as a biopesticide. The study synthesizes findings from various studies to provide a comprehensive understanding of the structural and functional aspects of Bt toxins, including the novel Vpb4Da2 protein with its unique six-domain architecture and receptor-binding regions, the broad-spectrum insecticidal activity of multiple Cry proteins, and the innovative use of chimeric proteins to enhance pest control. Additionally, the study explores the potential of Bt as a biofertilizer and its role in promoting plant growth while controlling phytopathogens. The insights gained from this study could pave the way for the development of more effective and sustainable pest management strategies. Keywords Bacillus thuringiensis; Cry toxins; Vpb4Da2 protein; Bioinsecticide; Genomic architecture 1 Introduction Bacillus thuringiensis (Bt) is a Gram-positive, spore-forming bacterium that is widely recognized for its insecticidal properties. It produces parasporal crystal proteins, known as Cry and Cyt toxins, during sporulation, which are highly toxic to a variety of insect larvae upon ingestion (Dorsch et al., 2002; Barbosa et al., 2015; Reyaz et al., 2019). These toxins have been extensively utilized in agricultural pest control as biopesticides, offering an environmentally friendly alternative to chemical insecticides (Nair et al., 2020). The bacterium's ability to produce a diverse array of toxins has made it a subject of significant interest in the field of integrated pest management (Crickmore et al., 2020). Understanding the genomic architecture of Bt is crucial for several reasons. Firstly, it allows for the identification and characterization of the genes responsible for its insecticidal properties, which can lead to the development of more effective biopesticides. Secondly, it provides insights into the genetic diversity and evolutionary mechanisms that enable Bt to adapt to different environmental conditions and host species (Barbosa et al., 2015). Additionally, knowledge of the genomic structure, including the presence of plasmids and their associated genes, can inform strategies for genetic engineering to enhance the bacterium's efficacy and spectrum of activity (Li et al., 2017; Crickmore et al., 2020). The study aims to provide a comprehensive overview of the current understanding of the genomic architecture of Bacillus thuringiensis. This includes an analysis of the functional elements within its genome, such as the coding sequences for Cry and Cyt toxins, and other virulence factors. The study hopes to synthesize findings from recent genomic studies to highlight the genetic basis of Bt's insecticidal properties and its potential applications in biocontrolmize the use of Bt in pest management. 2 Overview of Bt Genomic Structure Bacillus thuringiensis (Bt) is a gram-positive, spore-forming bacterium widely recognized for its insecticidal properties, primarily due to the production of crystal proteins (Cry and Cyt toxins). The genomic architecture of Bt is complex, comprising a circular chromosome and multiple plasmids that harbor genes responsible for its pathogenicity and adaptability (Figure 1) (Zhou et al., 2024).
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