Bt Research 2025, Vol.16, No.3, 110-117 http://microbescipublisher.com/index.php/bt 110 Research Insights Open Access Transcriptomic Responses of Bacillus thuringiensis to Environmental Stress Kai Chen, Jia Xuan Institute of Life Science, Jiyang College of Zhejiang A&F University, Zhuji, 311800, Zhejiang, China Corresponding author: jia.xuan@jicat.org Bt Research, 2025, Vol.16, No.3 doi: 10.5376/bt.2025.16.0014 Received: 19 Apr., 2025 Accepted: 30 May, 2025 Published: 18 Jun., 2025 Copyright © 2025 Chen and Xuan, 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: Chen K., and Xuan J., 2025, Transcriptomic responses of Bacillus thuringiensis to environmental stress, Bt Research, 16(3): 110-117 (doi: 10.5376/bt.2025.16.0014) Abstract Bacillus thuringiensis (Bt) is a commonly used biological control fungus. It will show different changes in gene expression when facing different environmental pressures. Previous studies have summarized the transcriptional reactions of Bt under conditions such as alkalinity, oxidation, salinity and ultraviolet light. It was found that Bt regulates its metabolism by up-regulating genes related to glycolysis, organic acid synthesis and antioxidant enzymes to adapt to external stress. At the same time, it also relies on regulatory factors such as Fur and σ factors to control iron absorption, hemoglobin synthesis, and antioxidant defense. It is precisely because of these regulations that Bt can survive for a long time in the natural environment and its host. However, there are still some deficiencies in the current research. For instance, the understanding of temporal transcriptomics under multiple stresses, the integration of different omics data, and the adaptation mechanisms in the natural environment is not yet in-depth enough. If multi-omics research and gene editing technology can be combined in the future, it will be possible to explain more clearly how Bt responds to environmental pressure, which will also help it play a greater role in ecological applications and industrial utilization. Keywords Bacillus thuringiensis; Transcriptome response; Environmental stress; Regulatory network; Multiomics integration 1 Introduction Bacillus thuringiensis (Bt) is a common Gram-positive bacillus and is widely used in agriculture and biological control. Its most prominent feature is its excellent insecticidal effect and its environmental friendliness. Bt can not only form spores that can tolerate harsh environments, but also produce various insecticidal proteins. Therefore, it plays a significant role in pest control and yield increase (Subramanian et al., 2021; Ali et al., 2022; Toukabri et al., 2022). However, in the natural environment, Bt often encounters many pressures, such as salt and alkali, heavy metals, ultraviolet rays and oxidative stress, etc. These factors will significantly affect its survival, reproduction and control effect (Barkad et al., 2021). Transcriptomic research has enabled us to observe the molecular responses and regulatory patterns of Bt in the face of these environmental pressures. Through the analysis of gene expression, it can be known how Bt regulates metabolic pathways, antioxidant systems, stress proteins and signal transduction, thereby adapting to the external environment. For instance, under alkaline conditions, Bt modulates genes for glycolysis and organic acid synthesis to enhance adaptability. Under iron deficiency and oxidative stress, it relies on Fur to regulate different iron chelase genes to maintain normal physiological states. Under multiple stresses such as salt stress, ultraviolet rays and antibacterial agents, it protects itself by regulating antioxidant enzymes, stress proteins and metabolic networks. These reactions not only affect the survival of Bt, but also influence the expression of its insecticidal protein and the control effect. This review compiles the transcriptome responses of Bt under various environmental stresses (such as salt and alkali, heavy metals, ultraviolet rays, oxidative stress, etc.), with a focus on gene regulation, changes in metabolic pathways, improvements in stress resistance, and the significance of these studies for biological control applications. Combining the latest transcriptome and proteome results, it is possible to better understand how Bt responds to environmental stress, thereby providing theoretical support for optimizing Bt strains and developing new biological control strategies (Li et al., 2018; Toukabri et al., 2022; Ma et al., 2023).
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