Molecular Soil Biology 2024, Vol.15, No.4, 183-192 http://bioscipublisher.com/index.php/msb 186 released into the soil via root exudates, pollen, and plant residues can interact with soil microorganisms, which play crucial roles in nutrient cycling and energy flow (Li et al., 2022) (Figure 1). Studies have shown that Bt crops can alter soil enzymatic activities, which are essential for maintaining soil health. For example, dehydrogenase and urease activities significantly increased under Bt crop cultivation, indicating potential positive effects on soil fertility (Li et al., 2019). However, the overall impact on soil fertility can vary depending on factors such as soil type, crop species, and agricultural practices (Icoz and Stotzky, 2008). Figure 1 Environmental behaviors of Bt protein (A) and its three-dimensional structures (B). I, II, and III: domains I, II, and III (Adopted from Li et al., 2022) 5.2 Risk of Bt toxin accumulation and microbial resistance development The persistence and accumulation of Bt toxins in the soil are critical concerns for environmental safety. Bt proteins can remain in the soil environment for extended periods, depending on factors like microbial activity, soil type, and climatic conditions (Icoz and Stotzky, 2008). While some studies have reported no significant adverse effects of Bt proteins on soil microbial communities (Zhaolei et al., 2018), others have highlighted the potential for Bt toxin accumulation to alter microbial dynamics and biodiversity. The risk of microbial resistance development is another concern, as continuous exposure to Bt toxins could lead to the selection of resistant microbial strains, potentially disrupting soil ecological balance (Li et al., 2022). 5.3 Ecological significance of microbial shifts on plant health and productivity Microbial communities in the soil are integral to plant health and productivity. Bt crops can induce shifts in these communities, which may have ecological implications. For instance, changes in the diversity and composition of bacterial and fungal communities in the rhizosphere of Bt maize have been observed, although these effects were often temporary and influenced more by seasonal factors than by the Bt trait itself (Wang et al., 2022). Additionally, Bt crops have been shown to affect beneficial mycorrhizal symbiosis, which is crucial for nutrient uptake and plant growth (Castaldini et al., 2005). While some studies suggest that Bt crops do not cause significant long-term changes in soil microbial communities (Zhaolei et al., 2018), the potential for subtle shifts that could impact plant health and productivity cannot be ignored (Castaldini et al., 2005; Icoz and Stotzky, 2008). 6 Interactions Between Bt Toxins and Other Soil Microorganisms 6.1 Antagonistic and synergistic interactions with beneficial soil bacteria Bt crops, which produce insecticidal proteins, have been scrutinized for their potential impacts on soil microbial communities. Studies have shown that Bt toxins can interact with beneficial soil bacteria, but these interactions
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