Antibacterial potential of green magnesium oxide nanoparticles against rice pathogen Acidovorax oryzae

[Display omitted] •The strain Acinetobacter johnsonii RTN1 was used as nanofactory to synthesize MgONPs.•Biogenic MgONPs were characterized through spectroscopic and imaging techniques.•Antibacterial activity of MgONPs against Acidovorax oryzae is being reported for the first time.•Substantial antibacterial activity was exhibited by the MgONPs in culture based tests and ultrastructure studies. Magnesium oxide nanoparticles (MgONPs) have emerged as effective antibacterial agents with unique physiochemical properties. Here, we report antibacterial activity of MgONPs produced by using Acinetobacter johnsonii strain RTN1 against rice pathogen Acidovorax oryzae for the first time. The physico-chemical and optical properties of biogenic MgONPs were elucidated by using UV–vis spectroscopy, FTIR, XRD, EDS, SEM, and TEM. Biogenic MgONPs showed substantial antibacterial activity (35.2 ± 0.61 mm zone of inhibition) against A. oryzae at 20 µg mL−1 and significantly reduced cell density (80.83% MIC at OD600) of pathogen in broth culture. The ultrastructure studies revealed the morphological disruptions in MgONPs-treated A. oryzae cells as compared to control. Hence, the MgONPs could be used to formulate a potent nanopesticide for A. oryzae.