Lactobacillus plantarum L-137 and/or ß-glucan impacted the histopathological, antioxidant, immune-related genes and resistance of Nile tilapia (Oreochromis niloticus) against Aeromonas hydrophila.

A trial was operated to assess the potential of using Lactobacillus plantarum L-137 (L-137) and/or ß-glucan (BG) in improving the resistance of Nile tilapia against Aeromonas hydrophila. Control diet and 3 diets supplemented with L-137, BG or L-137 + BG were prepared. Final body weight, specific growth rate, superoxide dismutase, and catalase showed considerably (P < .05) increased values in L-137 or L-137/BG groups, while glutathione peroxidase increased significantly (P < .05) only in L-137/BG group. Fish fed L-137 and/or BG diets showed that feed conversion ratio and malonaldehyde levels were significantly decreased (P < .05). Also, both L-137 and BG helped Nile tilapia to have high phagocytosis activity and relative expression of tumor necrosis factor-alpha (TNF-α) and interleukin 1 beta (IL-1ß) and interferon-gamma (INF-γ) genes. After A. hydrophila challenge, the intestinal villi epithelium of the L-137/BG group was intact and denser than the other groups. The hepatopancreas and spleen of the control group displayed severe necrosis in hepatocytes and congestion of blood sinusoids in addition to diffuse vacuolation. Regarding the L-137, BG and L-137/BG groups, there was a moderate and normal degree of vacuolation with focal necrosis and mild to moderate degree of congestion of blood sinusoids. Red blood cells, hemoglobin, and albumin showed meaningfully (P < .05) increased values in L-137 or L-137/BG groups. TNF-α, IL-1ß, and INF-γ expressions were upregulated by L-137 and/or BG. The obtained results revealed the ability of L-137 and/or BG to protect Nile tilapia from the effects of A. hydrophila infection by the motivation of the immune, antioxidative, and antiinflammation responses.

Synergetic Effects of Lactobacillus plantarum and ß-Glucan on Digestive Enzyme Activity, Intestinal Morphology, Growth, Fatty Acid, and Glucose-Related Gene Expression of Genetically Improved Farmed Tilapia.

The current study was conducted to evaluate the synergetic effects of heat-killed Lactobacillus plantarum (HK L-137) and ß-glucan (BG) on digestive enzyme activity and intestinal morphology of genetically improved farmed tilapia (GIFT) with focus on insulin-like growth factor I (IGF-I), fatty acid synthase (FAS), and glucose-6-phosphate dehydrogenase (G6PD). For 12 weeks, fish fed the control, or three diets incorporated with 100 HK L-137, 100 BG, or 50 HK L-137 + 50 BG mg/kg (HK L-137, BG, and HK L-137/BG diets). After final sampling, fish fed HK L-137 or HK L-137/BG diets exhibited significantly (P < 0.05) increased final body weight and weight gain while the specific growth rate and feed efficiency ratio enhanced only in HK L-137/BG group. Mucosal and villi lengths and muscle thickness significantly (P < 0.05) increased by HK L-137 or/and BG for the middle intestine. Lipase and protease improved significantly (P < 0.05) in fish fed both HK L-137 and BG when compared to the control group. Interestingly, qRT-PCR revealed a significant (P < 0.05) upregulation in the IGF-1 gene expression in fish fed HK L-137 or/and BG additives compared to the control. Muscle and liver G6PD gene expression were upregulated significantly (P < 0.05) in fish fed HK L-137/BG diet as compared to the control group. In addition, feeding HK L-137 or both additives effectively elevated the hematocrit, hemoglobin, and WBCs and decreased triglyceride and glucose levels. Accordingly, the use of both HK L-137 and BG is an efficient scheme to reach economically feasible and sustainable tilapia production.