Bacillus amyloliquefaciens protects Nile tilapia against Aeromonas hydrophila infection and alleviates liver inflammation induced by high-carbohydrate diet.

Carbohydrates are widely distributed in nature as an important nutritional substance and energy source. However, the utilization efficiency of carbohydrates is very poor in fish. Over consumption of carbohydrates will cause excessive inflammatory response and result in lower pathogen resistance in fish. Probiotics have been widely used to prevent inflammation, but the underlying mechanism still needs more exploration. In this study, three diets, including a control diet (CD), a high-carbohydrate diet (HD) and the HD supplemented with Bacillus amyloliquefaciens SS1 (HDB) were used to feed Nile tilapia for 10 weeks. At the end of the feeding trial, fish were challenged with Aeromonas hydrophila (A. hydrophila) for 7 days. The data showed that the addition of Bacillus amyloliquefaciens SS1 (B. amyloliquefaciens SS1) significantly increased the survival rate and enhanced the respiratory burst activity of head kidney leukocytes in Nile tilapia. B. amyloliquefaciens SS1 treatment significantly elevated the anti-oxidative capability, which was evidenced by higher activities of superoxide dismutase (SOD) and total antioxidant capacity (T-AOC), and higher content of reduced glutathione (GSH) in the serum. Administration with B. amyloliquefaciens SS1 effectively suppressed inflammatory response in the liver by inhibiting nuclear factor kappa-B (NF-κB)/interleukin-1 beta (IL-1ß) inflammatory signaling pathway. In vitro analysis suggested that intestinal bacteria derived-acetate has the antioxidant capability, which may account for the alleviation of inflammation. Overall, this study demonstrated that dietary supplementation with B. amyloliquefaciens SS1 protected Nile Tilapia against A. hydrophila infection and suppressed liver inflammation by enhancing antioxidant capability.

[Simultaneous Determination of Five Astragalosides in Astragali Radix and Jinqi Jiangtang Tablet by HPLC-ELSD].

OBJECTIVE: To develop an HPLC-ELSD method for simultaneous determination of Astragaloside IV Astragaloside I, Astragaloside II, Astragaloside III and Isostragaloside II in Astragali Radix and Jinqi Jiangtang tablet. METHODS: The chromatographic conditions were as follows: Grace Apollo C18 column (250 mm x 4. 6 mm, 5 µm), acetonitrile (A) and water(B) as mobile phases for gradient elution, and the flow rate being 1. 0 mL/min. RESULTS: Five components showed good linearity. The average recoveries were between 95% - 105%. Five Astragalosides were determined in twelve batches of Astragali Radix and ten batches of Jinqi Jiangtang tablet. CONCLUSION: This is a specific, sensitive and simple method for simultaneous determination of Astragaloside IV, Astragaloside I Astragaloside II, Astragaloside III and Isostragaloside II in Astragali Radix and Jinqi Jiangtang tablet.