Green synthesis and characterization of nanosilver derived from extracellular metabolites of potent Bacillus subtilis for antifungal and eco-friendly action against phytopathogen

• Published in: Biometals 2022-06, Vol.35 (3), p.479-497
• Main Authors: Gajera, H. P., Hirpara, Darshna G., Bhadani, Rushita V., Golakiya, B. A.
• Format: Article
• Language: English
• Subjects: Antifungal activity; Antifungal Agents - chemistry; Antifungal Agents - pharmacology; Bacillus; Bacillus subtilis; Bacillus subtilis - genetics; Bacillus subtilis - metabolism; Biochemistry; Biomedical and Life Sciences; Cell Biology; Cell membranes; Climate change; Electron transport; Environmental conditions; Fourier transforms; Functional groups; Fungicides; Fusarium oxysporum; Infrared spectroscopy; Leakage; Life Sciences; Lipid peroxidation; Lipids; Medicine/Public Health; Metabolites; Metal Nanoparticles - chemistry; Microbial Sensitivity Tests; Microbiology; Minimum inhibitory concentration; Mode of action; Nanoparticles; Nanostructures; Peroxidation; Pharmacology/Toxicology; Plant Physiology; Rhizosphere; RNA, Ribosomal, 16S - genetics; RNA, Ribosomal, 16S - metabolism; rRNA 16S; Silver; Silver nitrate; Spectroscopy, Fourier Transform Infrared; Sugar; Wilt
• ISSN: 0966-0844; 1572-8773
• DOI: 10.1007/s10534-022-00382-9

The potent antagonist Bacillus isolated from the soil rhizosphere elucidated the highest antagonism against the phytopathogen Fusarium oxysporum f. sp. cumini and was identified as Bacillus subtilis strain JSD-RSCu-8D based on molecular recognition by 16S rRNA sequencing (NCBI Accession No. KT894724). Live Bacillus may not work as effectively against phytopathogen under unfavorable environmental conditions like temperature, humidity, or other abiotic stresses. The extracellular metabolites, obtained from culturing potent B. subtilis, were exploited for the creation of green nanosilver for proficient actions in a changing climate. The synthesized green nanosilver was illustrated for shape (spherical with 65.21 ± 3.71 nm under SEM), size (70.9 nm in PSA), purity (2.69 keV peak corresponded to the binding energy of silver under EDAX), and stability (44.2 mV as ZETA). The formation of green Ag-NPs from extracellular metabolites was confirmed by a comparative appraisal of the electromagnetic peak of the metabolite's functional groups, silver nitrate, and green nanoparticles in Fourier transform infrared spectroscopy. The novel mode of action of pathogen mycelium degradation was elucidated by the minimum inhibitory concentration (MIC) of green nanosilver as 40 µg Ag ml −1 to diminish F. oxysporum (SEM morphology). The green nanosilver at 2 DAI renowned the leakage of sugars from mycelia of the cell membrane and defeated the activity of respiratory chain dehydrogenases, followed by lipid peroxidation and the highest leakage of proteins at 3 DAI on MIC. The in-vivo study might allow for novel insight to utilize green nanosilver at MIC (40 µg Ag ml −1 ) as an eco-friendly and fungicide alternate way for antifungal action to demolish Fusarium wilt infection under harsh conditions.