Green synthesis of ZnO nanoparticles using <i>Microbacterium arborescens</i>: a multifunctional approach in environment, health, and agriculture

ABSTRACT The investigation is about the biogenic fabrication of ZnO nanoparticles (ZnO NPs) using a microorganism Microbacterium arborescens. The synthesis process was optimized using various two pH (5 and 9) values and calcination temperatures (30 and 300 °C). UV–vis spectroscopic analysis has shown adsorption peaks and band gap energy of 393 nm, 3.16 eV as well as 359 nm, 3.46 eV for ZnO NPs pH 5 and pH 9, respectively. FTIR spectra confirmed the reduction of functional groups with increasing pH and temperature. The XRD analysis identified a hexagonal wurtzite structure with increasing crystallinity based on pH and calcination temperature. SEM images revealed a reduction in particle size with increasing pH and temperature, with average sizes of 46 nm at pH 9 and 300 °C. ZnO NPs were utilised for methylene blue (MB) dye removal, achieving 90.55% removal efficiency within 70 min at pH 9. The kinetics study shows better fitting (R2 &amp;gt; 0.9), indicating the chemisorption process. An antimicrobial activity was observed in 16 mm inhibition zones at 6 mg mL−1 concentration of ZnO NPs. Additionally, ZnO NPs enhanced seed germination in Vigna radiata, achieving 100% germination in 14 h. The study highlights biogenic synthesis as a sustainable approach for environmental remediation, medical, and agriculture applications.