Nuclear Agriculture Research School, Nuclear Science and Technology Research Institute, Karaj, 31465-1498, Iran.
Sci Rep. 2024 Feb 14;14(1):3720. doi: 10.1038/s41598-024-54380-7.
The aim of this study was to produce mutant strains of Bacillus subtilis with high probiotic performance for use in the aquaculture of rainbow trout Oncorhynchus mykiss. The main strain of B. subtilis (MS) was irradiated with gamma rays (5.3 KGy). Subsequently, the B. subtilis mutant strain no. 45 (MS. 45) was selected for bacterial growth performance, resistance to acidic conditions, resistance to bile salts and antibacterial activity against Aeromonas hydrophila and Pseudomonas fluorescens. After 60 days, the rainbow trout (70.25 ± 3.89 g) fed with MS. 45 and MS were exposed to hypoxia stress (dissolved oxygen = 2 ppm). Subsequently, immune indices (lysozyme, bacterial activity and complement activity), hematological indices [hematocrit, hemoglobin, WBC, RBC, mean corpuscular volume (MCV)] and antioxidant factors (T-AOC, SOD and MDA)) were analyzed after and before hypoxia exposure. The expression of immunological genes (IFN-γ, TNF-α, IL-1β, IL-8) in the intestine and the expression of hypoxia-related genes (HIF-1α, HIF-2α, FIH1) in the liver were compared between the different groups under hypoxia and normoxia conditions. Growth, immunological and antioxidant indices improved in group MS. 45 compared to the other groups. Stress indices and associated immunologic and hypoxia expressions under hypoxia and normoxia conditions improved in MS. 45 compared to the other groups. This resulted in improved growth, immunity and stress responses in fish fed with the microbial supplement of MS. 45 (P < 0.05) under hypoxia and normoxia conditions, (P < 0.05), resulting in a significant improvement in trout aquaculture.
本研究旨在获得具有高益生菌性能的枯草芽孢杆菌突变株，用于虹鳟鱼 Oncorhynchus mykiss 的水产养殖。主要枯草芽孢杆菌（MS）菌株经γ射线（5.3 KGy）照射。随后，选择枯草芽孢杆菌突变株 45 号（MS. 45）用于细菌生长性能、耐酸性、耐胆盐和对嗜水气单胞菌和荧光假单胞菌的抗菌活性。60 天后，用 MS. 45 和 MS 喂养的虹鳟（70.25±3.89 g）暴露于缺氧应激（溶解氧=2 ppm）下。随后，分析缺氧暴露前后免疫指标（溶菌酶、细菌活性和补体活性）、血液学指标[血细胞比容、血红蛋白、白细胞、红细胞、平均红细胞体积（MCV）]和抗氧化因子（T-AOC、SOD 和 MDA））。在缺氧和常氧条件下，比较了不同组间肠道中免疫基因（IFN-γ、TNF-α、IL-1β、IL-8）和肝脏中缺氧相关基因（HIF-1α、HIF-2α、FIH1）的表达。与其他组相比，MS 组的生长、免疫和抗氧化指标均有所提高。45 号组在缺氧和常氧条件下的应激指标以及相关免疫和缺氧表达均有所改善。与其他组相比，MS 组的生长、免疫和应激反应得到了改善。45 号（P<0.05），在缺氧和常氧条件下，显著改善了鳜鱼养殖。
