Bacillus cereus 0–9 is a biocontrol microorganism that antagonizes Gram-positive bacteria and pathogenic fungi, such as Staphylococcus aureus and Gaeumannomyces graminis, through the secretion of antimicrobial peptides. However, its low antibacterial activity limits its biocontrol application. In this study, a significant enhancement in antibacterial activity against S. aureus was achieved by overexpressing glucose dehydrogenase from Bacillus subtilis (BsGDH) in B. cereus 0–9, expanding the activity from 6.98 to 11.59 U/mL, representing a 66% improvement. To further improve its biocontrol capability, we aimed to improve the catalytic efficiency of BsGDH by screening 11 low-conserved residues in the protein’s second-shell via conservation analysis and molecular docking. Following three rounds of saturation mutagenesis, the specific enzyme activity and Kcat/Km value of the variant N97F/N192S/E198G reached to 289.74 U/mg and 4.95 µM⁻¹·min⁻¹, representing 5.66 and 11.38 times greater than that of the wild-type BsGDH, respectively. Molecular docking suggested that residues Gly94, Gly14, and Ile191 form a triangular region enhancing substrate affinity and enzymatic activity. Furthermore, the Root Mean Square Fluctuation analysis from molecular dynamics showed significant conformational changes in five regions of the mutants (α2 helix, α3 helix, α5 helix + β4 sheet, α8 helix + β5 sheet, and α13–14 helix), increasing the flexibility of the active pocket. Ultimately, the antibacterial activity of B. cereus 0–9 expressing N97F/N192S/E198G reached 22.79 U/mL, 2.26 times higher than that of B. cereus 0–9. This study offers a promising candidate for enhancing NAD(P)+ metabolic cycling and antimicrobial peptide synthesis in cells for industrial applications.

The primary resonance responses of high-performance nanocomposite materials used in spacecraft components in complex electromagnetic field environments were investigated. Simultaneously considering the interfacial effect, agglomeration effect, and percolation threshold, a theoretical model that can predict Young’s modulus and electrical conductivity of graphene nanocomposites is developed by the effective medium theory (EMT), shear lag theory, and the Mori-Tanaka method. The magnetoelastic vibration equation for an axially moving graphene nanocomposite current-carrying beam was derived via the Hamilton principle. The amplitude-frequency response equations were obtained for different external loading conditions. The study reveals the significant role of graphene concentration, external force, and magnetic field on the system’s primary resonance, highlighting how electromagnetic forces play a critical role similar to external excitation forces. It is shown that the increase in graphene content could lead the system from period-doubling motion into chaotic behavior. Moreover, an enhanced magnetic field strength may lower the minimum graphene concentration needed for period-doubling motion. This work provides new insights into controlling nonlinear vibrations of such systems through applied electromagnetic fields, emphasizing the importance of designing multifunctional nanocomposites in multi-physics coupled environments. The concentration of graphene filler would significantly affect the primary resonance and bifurcation and chaos behaviors of the system.