| Summary: | <i>Bt</i> proteins are crystal proteins produced by <i>Bacillus thuringiensis</i> (<i>Bt</i>) in the early stage of spore formation that exhibit highly specific insecticidal activities. The application of <i>Bt</i> proteins primarily includes <i>Bt</i> transgenic plants and <i>Bt</i> biopesticides. Transgenic crops with insect resistance (via <i>Bt</i>)/herbicide tolerance comprise the largest global area of agricultural planting. After artificial modification, <i>Bt</i> insecticidal proteins expressed from <i>Bt</i> can be released into soils through root exudates, pollen, and plant residues. In addition, the construction of <i>Bt</i> recombinant engineered strains through genetic engineering has become a major focus of <i>Bt</i> biopesticides, and the expressed <i>Bt</i> proteins will also remain in soil environments. <i>Bt</i> proteins expressed and released by <i>Bt</i> transgenic plants and <i>Bt</i> recombinant strains are structurally and functionally quite different from <i>Bt</i> prototoxins naturally expressed by <i>B. thuringiensis</i> in soils. The former can thus be regarded as an environmentally exogenous substance with insecticidal toxicity that may have potential ecological risks. Consequently, biosafety evaluations must be conducted before field tests and production of <i>Bt</i> plants or recombinant strains. This review summarizes the adsorption, retention, and degradation behavior of <i>Bt</i> insecticidal proteins in soils, in addition to their impacts on soil physical and chemical properties along with soil microbial diversity. The review provides a scientific framework for evaluating the environmental biosafety of <i>Bt</i> transgenic plants, <i>Bt</i> transgenic microorganisms, and their expression products. In addition, prospective research targets, research methods, and evaluation methods are highlighted based on current research of <i>Bt</i> proteins.
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