AUTHOR=Cheng Hai-Jun , Wang Hui , Zhang Jing-Ze 

TITLE=Phytofabrication of Silver Nanoparticles Using Three Flower Extracts and Their Antibacterial Activities Against Pathogen Ralstonia solanacearum Strain YY06 of Bacterial Wilt

JOURNAL=Frontiers in Microbiology

VOLUME=11

YEAR=2020

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2020.02110

DOI=10.3389/fmicb.2020.02110

ISSN=1664-302X

ABSTRACT=<p>Bacterial wilt caused by the phytopathogen <italic>Ralstonia solanacearum</italic> (<italic>R. solanacearum</italic>) is a devastating plant disease worldwide. The use of bactericides and antibiotics for controlling bacterial wilt has shown low efficiency and posed environmental risks. This study was to phytofabricate silver nanoparticles (AgNPs) mediated by canna lily flower (<italic>Canna indica</italic> L.), Cosmos flower (<italic>Cosmos bipinnata</italic> Cav.), and Lantana flower (<italic>Lantana camara</italic> L.). The biosynthesized AgNPs were confirmed and characterized by UV-visible spectroscopy, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), transmission electron microscope (TEM), and scanning electron microscopy (SEM). UV-visible spectra showed absorption peak bands at 448, 440, and 428 nm of AgNPs synthesized by <italic>C. indica</italic> L., <italic>C. bipinnata</italic> Cav., and <italic>L. camara</italic> L. flowers, respectively. FTIR spectra confirmed that biofunctional groups of flower extract were involved in the synthesis of AgNPs as capping and stabilizing agents. The spherical AgNPs synthesized by <italic>C. indica</italic> L., <italic>C. bipinnata</italic> Cav., and <italic>L. camara</italic> L. flowers had average diameters of 43.1, 36.1, and 24.5 nm, respectively. The AgNPs (10.0 μg/ml) synthesized by <italic>L. camara</italic> L. flower had a maximum suppression zone of 18 mm against <italic>R. solanacearum</italic> strain YY06 compared with AgNPs synthesized by <italic>C. indica</italic> L. and <italic>C. bipinnata</italic> Cav. flowers. Bacterial growth, biofilm formation, swimming motility, efflux of nucleic acid, cell death, cell membrane damage, and reactive oxygen species (ROS) generation of <italic>R. solanacearum</italic> were also negatively affected by AgNPs with high concentration and small size. In summary, the biosynthesized AgNPs can be used as an efficient and environmentally friendly antibacterial agent to reasonably inhibit <italic>R. solanacearum</italic>.</p>