Dietary Clostridium autoethanogenum protein modulates intestinal absorption, antioxidant status, and immune response in GIFT (Oreochromis niloticus) juveniles

This study investigated the effect of Clostridium autoethanogenum protein (CaP) on intestinal absorption, antioxidant status, and immune response of the genetically improved farmed tilapia (GIFT: Oreochromis niloticus) juveniles. The fish (initial weight 0.7 +/- 0.5 g) were fed with diets containing different levels of CaP: 0% (control), 5%, 10%, 15%, and 20% to partially replace soybean meal. After 8 weeks feeding trial, absorption capacity-related sodium/potassium-ATPase transporter (Na+/K+-ATP) was increased significantly by CaP levels; alkaline phosphatase (AKP) improved significantly by 5% and 10% CaP levels; while gamma-glutamyl transpeptidase (gamma-GT) was not significantly affected compared with the control diet. Malondialdehyde (MDA) content decreased significantly; glutathione (GSH) content and superoxide dismutase (SOD) activity increased significantly; while catalase (CAT) and glutathione peroxidase (GP-x) activities were not significantly affected by dietary CaP compared with the control. The expression of antioxidant-related genes: kelch-like ECH-associated protein 1 (Keap1), nuclear factor erythroid-2-related factor 2 (Nrf2) and glutathione peroxidase (GPx) were significantly down-regulated, up-regulated by 5% and 10%, and not significantly affected by CaP levels compared with the control diet, respectively. The immune-related target of rapamycin (TOR), peptide transporter 1 beta (Pept 1 beta), complementary component 3 (C3) and interferon-gamma (IFN-gamma) were significantly up-regulated by CaP levels; transforming growth factor-beta (TGF-beta) was only significantly up-regulated by 5% and 10% CaP; while interleukin-8 (IL-8) was not significantly affected compared with the control. Therefore, our results show that dietary CaP could enhance the intestinal absorption, antioxidant status, and immune response in GIFT juveniles. However, inclusion levels above 10% could harm the intestinal histology of the fish.

Automated summary

The study found that adding different levels of Clostridium autoethanogenum protein (CaP) can significantly improve the absorption capacity, antioxidant status, and immune response of genetically improved farmed tilapia (GIFT) juveniles. However, high levels of CaP may harm the intestinal histology of the fish.