Niallia Circulans mediated Bio-fabrication of ZnO nanoparticles: Synthesis, characterization, and multifunctional applications.

The current study addresses increasing global problems (agricultural sustainability, environmental contamination, and antimicrobial resistance) by means of sustainable and multifunctional biosynthesized Zinc oxide nanoparticles (ZnO NPs). The study utilized a cell-free supernatant of a novel endophytic bacterial strain (Niallia Circulans) to synthesize ZnO NPs. Biosynthesized NPs were evaluated by using various techniques of characterization. Surface plasmon resonance (SPR) was revealed by UV-Visible spectral peak for ZnO NPs at 355 nm. A X-ray diffraction (XRD) analysis confirmed a crystallite size of 90.64 nm, while scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX) demonstrated the predominance of hexagonal-structured zinc, carbon, and oxygen elements. The functional groups in Fourier transform infrared spectroscopy (FTIR) confirm the presence of biomolecules. The evaluated multifunctional application of biosynthesized ZnO NPs exhibits an enhanced early seedling growth rate and increased seed germination (100% in 12 h) on cowpea (Vigna unguiculata L.) compared to the control groups. Also shows excellent antibacterial activity against test bacterial strains. Additionally, a high removal efficiency of 97.85% was achieved within 110 min for 10 ppm methylene blue dye solution at pH 9. This study highlights the endophytic bacteria-mediated successful synthesis of ZnO NPs, with potential multifunctional applications in agriculture, antimicrobial treatments, and environmental remediation.