Abstract
Background: The gut microbiota of the silkworm (Bombyx mori) plays a vital role in metabolic processes, including nutrient digestion and immune regulation. However, the specific bacterial communities that enhance feed utilization and improve amino acid composition in silk and pupae remain unclear. In this study, we explored the mechanisms through which gut bacteria influence nutritional efficiency and the biosynthesis of high-quality silk and pupae by exposing fifth-instar silkworms to magnetic Fe₃O₄@urease-doped nanoconjugates. Results: Our findings revealed that Fe3O4@urease nanoconjugates had no detrimental effects on the silkworm gut. Dominant genera in the MF group included Enterococcus, Staphylococcus, Pantoea, Klebsiella and Glutamicibacter (p < 0.05), while Linear Discriminant Analysis (LDA) and Effect Size (LEfSe) identified Dialister, Rhizobium and Parabacteroides as biomarkers. Functional prediction revealed bacteria in the Fe3O4@urease nanoconjugates treatment group were involved in metabolic activities, including amino acid synthesis, protein degradation and immune development. HPLC-LC-MS analysis revealed significantly higher levels of the amino acids Histidine (1077.06%) and Arginine (1020.45%) in the Fe3O4@urease nanoconjugates treatment group. Conclusion: In summary, magnetic Fe₃O₄@urease-doped nanoconjugates effectively modulated B. mori gut microbiota, enhancing digestion and nutrient assimilation, and providing a scientific basis for the rational implementation of bacteria control for enhancing amino acid contents in silk and pupae.