Department of Biotechnology, College of Agriculture, Junagadh Agricultural University, Junagadh, Gujarat, 362001, India.
Biometals. 2022 Jun;35(3):479-497. doi: 10.1007/s10534-022-00382-9. Epub 2022 Mar 24.
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 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) as an eco-friendly and fungicide alternate way for antifungal action to demolish Fusarium wilt infection under harsh conditions.
从土壤根际中分离出的高效拮抗细菌 Bacillus 对病原菌尖孢镰刀菌（Fusarium oxysporum f. sp. cumini）表现出最高的拮抗作用，并通过 16S rRNA 测序（NCBI 注册号 KT894724）进行分子鉴定，被确定为枯草芽孢杆菌（Bacillus subtilis）菌株 JSD-RSCu-8D。在不利的环境条件下，如温度、湿度或其他非生物胁迫下，活体枯草芽孢杆菌可能无法有效地对抗病原菌。从高效枯草芽孢杆菌培养物中获得的胞外代谢产物被用于创建绿色纳米银，以在气候变化下发挥高效作用。合成的绿色纳米银在扫描电子显微镜下呈现出球形（SEM），平均粒径为 65.21 ± 3.71nm；在颗粒尺寸分析（PSA）中为 70.9nm；在能谱分析（EDAX）中，银的结合能对应 2.69keV 峰；在 ZETA 中为 44.2mV。通过比较代谢产物功能基团、硝酸银和绿色纳米粒子的电磁峰，证实了从胞外代谢产物中形成绿色 Ag-NPs。通过绿色纳米银的最小抑菌浓度（MIC）为 40μgAg ml，证实了其对病原菌菌丝降解的新型作用模式，可减少尖孢镰刀菌（SEM 形态）的生长。绿色纳米银在 2 DAI 时，就观察到细胞膜中的糖从菌丝中泄漏出来，并抑制了呼吸链脱氢酶的活性，随后在 3 DAI 时发生脂质过氧化和蛋白质的最大泄漏。体内研究可能为利用绿色纳米银在 MIC（40μgAg ml）下作为一种生态友好型和杀菌剂替代物提供新的见解，以在恶劣条件下消除枯萎病感染。
