This study evaluated the mortality rate, histopathology and haematological parameters of Arapaima gigas against Aeromonas hydrophila after 68 days of dietary probiotic supplementation with autochthonous bacterium Enterococcus faecium. Three experiments were carried out: the first assay evaluated the lethality of A. hydrophila, the second and the third assay evaluated the fish supplemented subjected to A. hydrophila lethal dose 30% (10⁶ CFU ml⁻¹) and lethal dose 100% (10⁸CFU ml⁻¹) respectively. The clinical signs, blood changes, histopathological alterations and mortalities were evaluated. At the first experiment, the concentrations of 10⁶ and 10⁸CFU.mL⁻¹ with A. hydrophila caused 33% and 100% of mortality. The A. hydrophila infection provoked clinical signs such as dark skin, ulceration, haemorrhage, pale gills and liver, hepatic alterations, hyperaemia, hepatic cord breakdown, cellular deforming, lipid degeneration and necrosis. In the second experiment, no mortality occurred onto fish fed with probiotic. Furthermore, in the third experiment, fish submitted to probiotic supplementation showed reduction in mortality of 75% compared with the control and fish fed with probiotic diets at 10⁸CFU g⁻¹ not presented any clinical signs. For these reasons, Arapaima gigas juveniles previously submitted to probiotic supplementation with E. faecium (10⁸CFU g⁻¹) shows better physiological and immunological response, improving resistance against A. hydrophila infection.

中文翻译：

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膳食补充益生菌粪肠球菌可提高巨骨舌鱼对嗜水气单胞菌的抵抗力

本研究评估了巨骨舌鱼对嗜水气单胞菌的死亡率、组织病理学和血液学参数，在 68 天的膳食益生菌补充与本土细菌粪肠球菌后。进行了三个实验：第一个试验评估了A的杀伤力。亲水性，第二个和第三个测定评估了补充了A的鱼。嗜水菌致死剂量 30% (10 ⁶  CFU ml ^-1 ) 和致死剂量 100% (10 ⁸ CFU ml ^-1） 分别。评估临床体征、血液变化、组织病理学改变和死亡率。在第一个实验中，10 ⁶和 10 ⁸ CFU.mL ^-1与A的浓度。 嗜水菌导致 33% 和 100% 的死亡率。一个。  _ 嗜水菌感染引起的临床症状包括皮肤变黑、溃疡、出血、鳃和肝脏苍白、肝脏改变、充血、肝索破裂、细胞变形、脂质变性和坏死。在第二个实验中，喂食益生菌的鱼没有死亡。^{此外，在第三个实验中，补充益生菌的鱼与对照组相比死亡率降低了 75%，喂食 10 8} CFU g ^-1益生菌日粮的鱼没有出现任何临床症状。由于这些原因，巨巨骨舌鱼幼鱼以前曾接受过补充大肠杆菌的益生菌。 粪便(10 ⁸ CFU g ^-1) 表现出更好的生理和免疫反应，提高了对A 的抵抗力。 嗜水菌感染。