Multi-omics reveals taxonomic and functional adaptations of soil microbiota to Bt toxin exposure

Bt toxins released from transgenic Bt plants exhibit biocidal activity and are considered exogenous environmental hazards in soil ecosystems. Here, we employed an integrated multi-omics approach to systematically characterize the taxonomic and functional regulatory mechanisms and adaptive strategies of soil microorganisms in response to Bt toxin exposure across a gradient of concentrations. Our findings demonstrate that different application amounts of Bt toxins significantly influenced both toxin persistence in soil and the soil nutrition multifunctionality (SNM) index. Notably, none of the tested Bt toxin concentrations exerted adverse effects on the diversity or complexity of soil microbial communities. Correlation analysis revealed that SNM was significantly positively associated with bacterial α-diversity (Sobs and Shannon indices) and microbial network edge numbers, but showed no such association with fungal communities, indicating distinct response patterns between soil bacteria and fungi to Bt toxin exposure. Divergent responses were also observed in the taxonomic and functional diversity of microbial communities under Bt toxin addition. Comparative transcriptomic analysis between Bt500_100 and Bt0_100 samples revealed that microorganisms downregulated energy metabolism pathways while upregulating genes associated with cell motility and environmental adaptation. These results collectively indicate that soil microorganisms employ adaptive metabolic strategies to mitigate nutrient limitation induced by the declining bioavailability of Bt toxin in soil environments.