The present study deals with the preparation and optimisation of neem oil nanoemulsion by microfluidization process and its application for the bacterial infection management in aquaculture. The effect of process parameters like surfactant concentration (Tween 20, Tween 80), homogenisation pressure and the number of cycles on the droplet size of neem oil nanoemulsion was investigated. The optimized pressure and number of cycles for the neem oil nanoemulsion preparation was found to be 20,000 psi and 25 cycles respectively. A significant decrease (p < 0.05) in the particle size of neem oil nanoemulsion was observed as the pressure, number of cycles and concentration of surfactant increase. The neem oil nanoemulsion prepared using 1:3 ratio of neem oil and Tween 80 surfactant showed a good stability with a mean droplet size of 24.5 ± 1.33 nm. The concentration of Azadiractin, an active ingredient in neem oil nanoemulsion was found to be 21.187 ± 1.01 μg/mL. The 1:3 ratio of neem oil ‐ Tween 80 formulated nanoemulsion showed good antibacterial activity against the fish pathogen, Aeromonas culicicola (MIC of 0.93 μl/mL). The morphological changes inflicted by the neem nanoemulsion treatment on bacterial cells were evident from the scanning electron microscopy and membrane integrity analysis. Further, the In‐vivo bactericidal efficacy of the neem oil nanoemulsion was tested on Common carp (Cyprinus carpio). The neem oil nanoemulsion treatment exhibited protective action against Aeromonas culicicola infection and it improved the antioxidant defence system of fish. The above results envisage the use of neem oil nanoemulsion as a potential alternative for synthetic antibiotics in treatment of bacterial infection of the fish.

中文翻译：

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纳米印em油的微流化乳化及其对鲤鱼中Aculmonaco culicicola感染的治疗潜力

本研究涉及通过微流化工艺制备和优化印e油纳米乳液及其在水产养殖细菌感染管理中的应用。研究了工艺参数如表面活性剂浓度（吐温20，吐温80），均质压力和循环次数对印em油纳米乳液液滴尺寸的影响。印em油纳米乳液制剂的最佳压力和循环数分别为20,000 psi和25个循环。随着压力，循环次数和表面活性剂浓度的增加，印ne油纳米乳液的粒径显着降低（p <0.05）。使用印ne油和吐温80表面活性剂的比例为1：3制备的印em油纳米乳液显示出良好的稳定性，平均液滴尺寸为24.5±1.33 nm。发现印ne油纳米乳中的活性成分阿扎地西汀的浓度为21.187±1.01μg/ mL。印em油-吐温80纳米乳液的1：3比例显示出对鱼类病原体的良好抗菌活性，气单胞菌a（MIC为0.93μl / mL）。印em纳米乳剂处理对细菌细胞造成的形态变化从扫描电子显微镜和膜完整性分析中可以明显看出。此外，在Common鱼（Cyprinus carpio）上测试了印em油纳米乳剂的体内杀菌效果。印em油纳米乳液处理对库车气单胞菌感染具有保护作用，并改善了鱼的抗氧化防御系统。上述结果设想使用印em油纳米乳剂作为合成抗生素治疗鱼类细菌感染的潜在替代品。