Fish disease is a major threat affecting the long-term development of aquaculture industry leading to great economic loss annually. Aeromonas hydrophila bacterium may be a primary or secondary cause of ulcers, hemorrhagic septicemia, fin rot and tail rot in fishes. Excess and abandoned usage of antibiotic substances caused a substantial growth of antibiotic resistant pathogens. Now a days, enduring research has focused on improvement of nanomaterials for efficient antimicrobial therapies. Comparing to the synthesis of other metallic nanoparticles, silver nanoparticles (AgNPs) has gained much attention because of its unique antimicrobial properties. The present study was aimed to green synthesize AgNPs using the Annona squamosa leaf extract which acts as a non-toxic reducing agent. The synthesized AgNPs were evaluated for biocompatibility and antagonistic efficacy against A. hydrophila. The green synthesized AgNPs were bio-physically characterized by UV-Visible spectroscopy, X-ray powder diffraction, High Resolution Transmission Electron Microscope, Fourier-transform infrared spectroscopy and Zeta Potential analysis. The particles were almost spherical shaped and in the range of 15-25 nm. Green synthesized AgNPs exhibited significant DPPH radical scavenging activity (64.62 %). Synthesis of AgNPs using widely available plants can be promoted as a potential eco-friendly option to chemical methods used for nanosynthesis. In-vivo studies confirmed that the AgNPs exhibited good antagonistic against A. hydrophila and also proved its non-toxic effect to Artemia salina nauplii.

中文翻译：

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使用无节肢动物评估绿色合成的银纳米颗粒对水生病原体嗜水气单胞菌的作用

鱼病是影响水产养殖业长期发展的主要威胁，每年造成巨大的经济损失。嗜水气单胞菌细菌可能是鱼类溃疡，出血性败血病，鳍腐烂和尾巴腐烂的主要原因。抗生素物质的过量使用和废弃导致抗生素抗性病原体的大量生长。如今，持续的研究集中在改进纳米材料上，以进行有效的抗菌治疗。与其他金属纳米粒子的合成相比，银纳米粒子（AgNPs）由于其独特的抗菌特性而受到了广泛的关注。本研究旨在使用番荔枝绿（Annona squamosa）绿色合成AgNP。叶提取物，用作无毒还原剂。评估合成的AgNPs的生物相容性和拮抗亲水杆菌的功效。通过紫外可见光谱，X射线粉末衍射，高分辨率透射电子显微镜，傅里叶变换红外光谱和Zeta电位分析对绿色合成的AgNP进行生物物理表征。颗粒几乎是球形的并且在15-25nm的范围内。绿色合成的AgNPs表现出显着的DPPH自由基清除活性（64.62％）。可以推广使用广泛可用的植物合成AgNPs，作为纳米合成化学方法的一种潜在的生态友好选择。体内研究证实，AgNPs具有良好的拮抗作用亲水链球菌也证明了其对卤虫无节幼体的无毒作用。