The present research explored the effects of Bacillus subtilis on water quality, growth, immune responses, endotoxemia and protection against lipopolysaccharide (LPS) damages in Nile tilapia Oreochromis niloticus under biofloc system. B. subtilis was added at 0, 1, 2, 3 and 4 grams (1.19 × 10⁸ CFU/g) per kg of basal diet, named T1 (control), T2, T3, T4 and T5, respectively, and fed to fish (14.82 ± 0.42 g) for 50 days. The concentrations of TAN, NO₂ and NO₃ were significantly reduced, and fish fed probiotics displayed significantly better growth performances versus the control, concomitantly with significantly enhanced activities of digestive enzymes. They also showed significantly declined serum glucose and cholesterol vice versa significantly improved immune responses (total protein, albumin, globulin, lysozyme, alternative complement, protease, immunoglobulins, alkaline phosphatase and respiratory burst), antioxidant capacity (superoxide dismutase, total antioxidant capacity, malondialdehyde) and skin mucus parameters (total protein, lysozyme, alternative complement, protease, immunoglobulins). Meanwhile, significantly lower endotoxin (LPS) concentrations were detected in the intestines and serum of fish fed probiotics. LPS challenge induced profound oxidative stress and impaired immune responses. Interestingly, probiotic alleviated LPS‐induced damages and restored mentioned parameters. In conclusion, B. subtilis effectively enhanced fish production, immunity and protection against LPS‐induced damages in tilapia under biofloc system.

中文翻译：

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生物絮凝技术系统下枯草芽孢杆菌对尼罗罗非鱼水质，生长，免疫反应，内毒素血症和脂多糖诱导的损害的有益作用

本研究探讨的影响枯草芽孢杆菌对水质，生长，免疫反应，内毒素血症和防止脂多糖（LPS）损害赔偿尼罗罗非鱼尼罗罗非鱼在生物絮凝系统。枯草芽孢杆菌的添加量为 每公斤基础日粮0、1、2、3和4克（1.19×10 ⁸ CFU / g），分别命名为T1（对照），T2，T3，T4和T5，并喂入鱼（14.82±0.42 g）50天。TAN，NO ₂和NO ₃的浓度鱼类的益生菌含量显着降低，与对照组相比，益生菌的生长性能显着提高，同时消化酶的活性也显着提高。他们还显示血清葡萄糖和胆固醇水平显着下降，反之亦然，显着改善了免疫反应（总蛋白，白蛋白，球蛋白，溶菌酶，替代补体，蛋白酶，免疫球蛋白，碱性磷酸酶和呼吸爆发），抗氧化能力（超氧化物歧化酶，总抗氧化能力，丙二醛） ）和皮肤粘液参数（总蛋白，溶菌酶，替代补体，蛋白酶，免疫球蛋白）。同时，在喂食益生菌的鱼的肠和血清中检测到的内毒素（LPS）浓度明显降低。LPS挑战引起了深刻的氧化应激和免疫反应受损。有趣的是，益生菌减轻了LPS引起的损害并恢复了上述参数。结论，在生物絮凝系统下，枯草芽孢杆菌有效地提高了鱼类产量，免疫力并保护了罗非鱼对LPS造成的损害。